1. A positively charged particle follows a circular path as shown below. Which of the following electric fields could have caused the charged particle to follow the above path? (Total 1 mark) 2. Two isolated point charges, –7 μC and +2 μC, are at a fixed distance apart. At which point is it possible for the electric field strength to be zero? (not to scale) (Total 1 mark) IB Questionbank Physics 1 3. This question is about electric charge. (a) A plastic rod XY is held at end X. The end Y is rubbed with a piece of cloth and, as a result, the end Y becomes electrically charged. The procedure is now repeated using a copper rod and it is found that the copper rod remains electrically neutral. Explain these observations in terms of the properties of conductors and insulators. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (5) IB Questionbank Physics 2 (b) Two plastic rods each have a positive charge +q situated at one end. The rods are arranged as shown. Assume that the charge at the end of each rod behaves as a point charge. Draw, in the shaded area on the diagram, the electric field pattern due to the two charges. (2) (Total 7 marks) IB Questionbank Physics 3 4. The diagram below shows a uniform electric field of strength E. The field is in a vacuum. An electron enters the field with a velocity v in the direction shown. The electron is moving in the plane of the paper. The path followed by the electron will be A. parabolic. B. in the direction of E. C. in the direction of v. D. circular. (Total 1 mark) IB Questionbank Physics 4 5. This question is about electric charge and resistance. (a) A plastic rod XY is held at end X. The end Y is rubbed with a piece of cloth and, as a result, the end Y becomes electrically charged. The procedure is now repeated using a copper rod and it is found that the copper rod remains electrically neutral. Explain these observations in terms of the properties of conductors and insulators. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (5) IB Questionbank Physics 5 (b) Two plastic rods each have a positive charge +q situated at one end. The rods are arranged as shown. Assume that the charge at the end of each rod behaves as a point charge. Draw, in the shaded area on the diagram (i) the electric field pattern due to the two charges. (2) (ii) a line to represent an equipotential surface. Label the line with the letter V. (1) (c) A resistor of resistance 1.5 Ω is made from copper wire of radius 0.18 mm. The resistivity of copper is 1.7 × 10–8 Ω m. Determine the length of copper wire used to make the resistor. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (2) IB Questionbank Physics 6 (d) The manufacturer of the resistor in (c) guarantees that the resistance is within 10 % of 1.5 Ω , provided that the power dissipation in the resistor does not exceed 1.0 W. (i) Suggest why the resistance of the resistor might be greater than 1.65 Ω if the power dissipation in the resistor is greater than 1.0 W. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (2) (ii) Show that, for a power dissipation of 1.0 W, the current in a resistor of resistance 1.5 Ω is 0.82 A. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (1) IB Questionbank Physics 7 (iii) The 1.5 Ω resistor is connected in series with a variable resistor and battery of emf 6.0 V and internal resistance 1.8 Ω. Estimate the resistance R of the variable resistor that will limit the current to 0.82 A. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (3) (Total 16 marks) 6. Three positive point charges of equal magnitude are held at the corners X, Y and Z of a right-angled triangle. The point P is at the midpoint of XY. Which of the arrows shows the direction of the electric field at point P? (Total 1 mark) IB Questionbank Physics 8 7. The diagram shows two parallel metal plates X and Y. Plate X is at Earth potential (0 V) and the potential of plate Y is V0. Which of the following is correct in respect of the magnitude and the direction of the electric field between the plates? Magnitude Direction A. constant X→Y B. increasing Y→X C. constant Y→X D. increasing X→Y (Total 1 mark) IB Questionbank Physics 9 8. The radius of a charged spherical conductor is R. Which of the following graphs best shows how the magnitude of the electrical field strength E varies with distance r from the centre of the sphere? (Total 1 mark) 9. Which of the following gives the acceleration of an electron of electric charge e and mass m in a uniform electric field of strength E? A. E B. Ee C. Ee m D. m Ee (Total 1 mark) IB Questionbank Physics 10 10. This question is about electric and gravitational fields (a) State, in terms of electrons, the difference between a conductor and an insulator. ...................................................................................................................................... ...................................................................................................................................... (1) (b) Suggest why there must be an electric field inside a current-carrying conductor. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (3) (c) The magnitude of the electric field strength inside a conductor is 55 N C–1. Calculate the force on a free electron in the conductor. ...................................................................................................................................... ...................................................................................................................................... (1) (d) The electric force between two point charges is a fundamental force as is the gravitational force between two point masses. State one similarity between these two forces and one difference (other than the fact that one applies to charge and the other to mass). Similarity: ................................................................................................................... ...................................................................................................................................... Difference: .................................................................................................................. ...................................................................................................................................... (2) IB Questionbank Physics 11 (e) The force on a mass of 1.0 kg falling freely near the surface of Jupiter is 25 N. The radius of Jupiter is 7.0 × 107 m. (i) State the value of the magnitude of the gravitational field strength at the surface of Jupiter. ........................................................................................................................... (1) (ii) Calculate that the mass of Jupiter is about 1.8 × 1027 kg. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (2) (Total 10 marks) 11. This question is about electric fields and electrical resistance. (a) State, in terms of electrons, the difference between a conductor and an insulator. ...................................................................................................................................... ...................................................................................................................................... (1) (b) Suggest why there must be an electric field inside a current-carrying conductor. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (3) IB Questionbank Physics 12 (c) The magnitude of the electric field strength inside a conductor is 55 N C–1. Calculate the force on a free electron in the conductor. ...................................................................................................................................... ...................................................................................................................................... (1) (d) Define resistance. ...................................................................................................................................... ...................................................................................................................................... (1) (e) A resistor made from a metal oxide has a resistance of 1.5 Ω. The resistor is in the form of a cylinder of length 2.2 × 10–2 m and radius 1.2 × 10–3 m. Calculate the resistivity of the metal oxide. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (2) (f) The manufacturer of the resistor in (e) guarantees its resistance to be within ±10 % of 1.5 Ω provided the power dissipation in the resistor does not exceed 1.0 W. Calculate the maximum current in the resistor for the power dissipation to be equal to 1.0 W. ...................................................................................................................................... ...................................................................................................................................... (2) IB Questionbank Physics 13 (g) Three of the resistors in (f) are connected in the circuit below. The cell has an emf of 2.0 V and negligible internal resistance. (i) Define emf. ........................................................................................................................... ........................................................................................................................... (1) (ii) Determine the minimum and the maximum power that could be dissipated in this circuit. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (3) (Total 14 marks) IB Questionbank Physics 14 12. Which arrangement of three point charges at the corner of an equilateral triangle will result in a zero electric field strength at the centre of the triangle, point P? (Total 1 mark) 13. This question is about a lightning discharge. (a) Define electric field strength. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (2) IB Questionbank Physics 15 (b) A thundercloud can be modelled as a negatively charged plate that is parallel to the ground. The magnitude of the charge on the plate increases due to processes in the atmosphere. Eventually a current discharges from the thundercloud to the ground. On the diagram, draw the electric field pattern between the thundercloud base and the ground. (3) IB Questionbank Physics 16 (c) The magnitude of the electric field strength E between two infinite charged parallel plates is given by the expression E= 0 where σ is the charge per unit area on one of the plates. A thundercloud carries a charge of magnitude 35 C spread over its base. The area of the base is 1.2 × 107 m2. (i) Determine the magnitude of the electric field between the base of the thundercloud and the ground. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (3) (ii) State two assumptions made in (c)(i). 1. ....................................................................................................................... ........................................................................................................................... 2. ....................................................................................................................... ........................................................................................................................... (2) IB Questionbank Physics 17 (iii) When the thundercloud discharges, the average discharge current is 1.8 kA. Estimate the discharge time. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (3) (iv) The potential difference between the thundercloud and the ground before discharge is 2.5 × 108 V. Determine the energy released in the discharge. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (4) (Total 17 marks) 14. This question is about a lightning discharge. (a) Define electric field strength. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (2) IB Questionbank Physics 18 (b) A thundercloud can be modelled as a negatively charged plate that is parallel to the ground. The magnitude of the charge on the plate increases due to processes in the atmosphere. Eventually a current discharges from the thundercloud to the ground. On the diagram, draw the electric field pattern between the thundercloud base and the ground. (3) (c) The current discharges when the magnitude of the electric field between the ground and the thundercloud base is 0.33 MN C–1. The thundercloud base is 750 m above the ground. (i) Calculate, just before discharge, the potential difference between the thundercloud base and the ground. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (3) IB Questionbank Physics 19 (ii) The potential difference V, between the thundercloud base and the ground, is given by V= Qd A 0 where Q is the charge on the thundercloud base, A is the area of the base, and d is the distance between the base and the ground. The area of the base is 1.2 × 107 m2. Calculate, just before discharge, the charge on the base of the thundercloud. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (2) (iii) Determine the energy released in the discharge. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (4) (Total 14 marks) IB Questionbank Physics 20 15. Which diagram best represents the electric field due to a negatively charged conducting sphere? (Total 1 mark) 16. This question is about electric fields and electric circuits. (a) Two parallel, charged metal plates A and B are in a vacuum. At a particular instant an electron is at point P. On the diagram, draw (i) the electric field pattern due to the plates. (3) IB Questionbank Physics 21 (ii) an arrow to represent the direction of the force on the electron at P. (1) (b) The acceleration of the electron at P is 8.8 × 1014 m s–2. Determine the magnitude of the electric field strength at the point P. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (3) (c) The electric potential energy of the electron changes by 1.9 × 10–17 J as it moves from one plate to the other. Show that the potential difference between the plates is 120 V. ...................................................................................................................................... ...................................................................................................................................... (1) (d) A resistor R and a filament lamp L are connected in series with a battery. The battery has an emf of 12 V and internal resistance 4.0 Ω. The potential difference across the filament of the lamp is 3.0 V and the current in the filament is 0.25 A. IB Questionbank Physics 22 (i) Define emf and describe the concept of internal resistance. emf: ........................................................................................................................... ........................................................................................................................... Internal resistance: ........................................................................................................................... ........................................................................................................................... (2) (ii) Calculate the total power supplied by the battery. ........................................................................................................................... ........................................................................................................................... (1) (iii) Calculate the power dissipated in the external circuit. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (2) (iv) Determine the resistance of the resistor R. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (3) (Total 16 marks) IB Questionbank Physics 23 17. This question is about electric fields and electric circuits. (a) Two parallel, charged metal plates A and B are in a vacuum. At a particular instant an electron is at point P. On the diagram, draw (i) the electric field pattern due to the plates. (3) (ii) an arrow to represent the direction of the force on the electron at P. (1) (b) The acceleration of the electron at P is 8.8× 1014 m s–2. Determine the magnitude of the electric field strength at the point P. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (3) (c) The electric potential energy of the electron changes by 1.9 × 10–17 J as it moves from one plate to the other. Show that the potential difference between the plates is 120 V. ...................................................................................................................................... ...................................................................................................................................... (1) (d) A resistor R and a filament lamp L are connected in series with a battery. The battery has an emf of 12 V and internal resistance 4.0 Ω. The potential difference across the filament IB Questionbank Physics 24 of the lamp is 3.0 V and the current in the filament is 0.25 A. (i) Calculate the total power supplied by the battery. ........................................................................................................................... ........................................................................................................................... (1) (ii) Calculate the power dissipated in the external circuit. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (2) IB Questionbank Physics 25 (iii) Determine the resistance of the resistor R. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (3) (Total 14 marks) 18. This question is about motion of a charged particle in an electric field. (a) An α-particle of mass 4u and charge +2e is accelerated from rest in a vacuum through a potential difference of 2.4 kV. Show that the final speed of the α-particle is 4.8 × 105 m s–1. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (2) (b) The α-particle is travelling in a direction parallel to and mid-way between two parallel metal plates. (not to scale) The metal plates are of length 2.4 cm and their separation is 0.80 cm. The potential difference between the plates is 600 V. The electric field is uniform in the region between the plates and is zero outside this region. IB Questionbank Physics 26 (i) Calculate the magnitude of the electric field between the plates. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (2) (ii) Show that the magnitude of the acceleration of the α-particle by the electric field is 3.6 × 1012 m s–2. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (2) (c) (i) Calculate the time taken for the α-particle to travel a horizontal distance of 2.4 cm parallel to the plates. ........................................................................................................................... ........................................................................................................................... (1) (ii) Use your answers in (b)(ii) and (c)(i) to deduce whether, as the α-particle passes between the plates, it will hit one of the plates. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... (3) (Total 10 marks) IB Questionbank Physics 27 19. Which of the following diagrams illustrates the electric field pattern of a negatively charged sphere? (Total 1 mark) 20. This question is about gravitational and electric fields. (a) The equation for the magnitude of the gravitational field strength due to a point mass may be written as below. Y= KX s2 The equation for the magnitude of the electric field strength can also be written in the same form. In the table identify the symbols used in the equation. Symbol Gravitational field quantity Electrical field quantity Y K X s (4) IB Questionbank Physics 28 (b) The magnitude of the electrostatic force between the proton and electron in a hydrogen atom is FE. The magnitude of the gravitational force between them is FG. Determine the ratio FE . FG ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (3) (Total 7 marks) IB Questionbank Physics 29 21. Four point charges of magnitudes +q, +q, –q, and –q are held in place at the corners of a square of side r. The Coulomb constant is k. Which of the following is the electrical potential at the centre of the square O? A. 0 B. 4kq r C. 4kq 2 r D. − 4 kq 2 r2 (Total 1 mark) IB Questionbank Physics 30 22. The diagram below shows a particle with positive charge q accelerating between two conducting plates at potentials V1 and V2. Which of the following is the kinetic energy gained by the charge in moving between the plates? A. V2q B. V1q C. (V1 – V2)q D. (V2 – V1)q (Total 1 mark) 23. A test charge is a A. charged object with a very small mass. B. charged object with a very small charge. C. point charge which has no effect on the electric field in which it is placed. D. point charge which slightly changes the electric field in which it is placed. (Total 1 mark) IB Questionbank Physics 31 24. This question is about gravitational and electric fields. (a) The equation for the magnitude of the gravitational field strength due to a point mass may be written as below. Y= KX s2 The equation for the magnitude of the electric field strength can also be written in the same form. In the table identify the symbols used in the equation. Symbol Gravitational field quantity Electrical field quantity Y K X s (4) (b) The magnitude of the electrostatic force between the proton and electron in a hydrogen atom is FE. The magnitude of the gravitational force between them is FG. Determine the ratio FE . FG ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (3) (Total 7 marks) IB Questionbank Physics 32 25. The electric field strength at a point may be defined as A. the force exerted on unit positive charge placed at that point. B. the force per unit positive charge on a small test charge placed at that point. C. the work done on unit positive charge to move the charge to that point from infinity. D. the work done per unit positive charge to move a small test charge to that point from infinity. (Total 1 mark) IB Questionbank Physics 33
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