Honors Physics: Semester 2 Final Review: part 2 Waves Key Ideas: ● know the definition of a wave ● know all your vocab, there’s a lot (amplitude, crest, trough, rarefaction, phase,….) ● know the different wave parameters (frequency, wavelength,..) their units, and how to identify them using the graph of a wave ● know the difference between transverse vs. longitudinal and mechanical vs. electromagnetic waves, and know examples of each ● know the relationship between frequency, wavelength and velocity of a wave and know how to apply the equation v = fλ ● know which factors affect the velocity of a wave and which don’t ● know the definitions and characteristics of the various wave behaviors we’ve discussed (refraction, interference, resonance, standing wave,…) and be able to give an example of each type of behavior ● know which wave properties are affected by each type of behavior ● be able to draw the resultant wave pattern from two interfering wave pulses ● understand the concept of resonance and when it occurs ● be able to both draw and identify harmonic patterns for the three cases of resonance we studied: resonance on a guitar string, resonance in a tube open at both ends, and resonance in a tube closed at one end ● know, and be able to apply the equations for calculating the fundamental frequency and the higher harmonics for the three types of media mentioned in the previous bullet ● be able to tell from a looking at a picture of a ray a light going from one medium to another whether the ray is bending towards or away from the normal, which medium is more dense, and which has a higher index of refraction ● understand what an index of refraction is and what it tells about the speed of light in different media ● know Snell’s law and be able to apply it when solving problems ● know the conditions for total internal reflection and how to solve for the critical angle above which total internal reflection occurs ● know what the Doppler effect ● know the Doppler effect equation and be able to use it when solving problems Practice Problems 1. What is the wavelength of a sound wave with a frequency of 1000 Hz and a speed of 344 m/s? 2. A radar antenna emits electromagnetic radiation (c = 3.0 x 108 m/s) with a wavelength of 0.03 m for 0.050 s. a) What’s the frequency of the radiated wave? b) How many complete waves are emitted in this time interval? c) After 10.0 seconds, how far is the front of the wave from the antenna? 3. For a given type of wave, periodic waves with a higher frequency will have _________ wavelengths than those with lower frequencies. 4. Why doesn’t sound travel in a vacuum? 5. The distance between two successive crests of an ocean wave is 13.0 m. The time between successive crests is 7.5 sec. a) Determine the period and frequency of the waves. b) Determine the speed of the waves. 6. The time required for an object to complete one cycle of motion is called ______________. 7. Waves that cannot exist without a medium to travel through are called _______________ waves. 8. The maximum displacement of a particle from its equilibrium position is called _________________. 9. A _______________wave’s particles vibrate in the same direction as the wave motion. 10. The ____________ of a mechanical wave is constant even when the medium changes. 11. A wave generator produces 17 waves every 10 sec. What’s the period of the waves being generated? 12. Lower frequency sound waves will have a higher pitch. T F 13. A Slinky-spring is shaken up and down 5 times in 3.8 s. The wave pattern produced looks like the below wave. Label the crest, trough, wavelength and amplitude. Calculate the frequency, period, wavelength and speed of the wave. 14. The graph below displays how displacement varies with time when a wave passes a fixed point at a speed of 14m/s. Calculate the frequency and wavelength of the wave. 1 15. A standing wave is produced in a thin strip of metal at a frequency of 175 Hz. The anti-nodes in the pattern are 12 cm apart. For the waves in the metal strip find the following: (a) wavelength, and (b) speed 16. When sound passes from air into water A) its frequency does not change. B) its wavelength does not change. C) its velocity does not change. What is this behavior called? 17. A string fixed at both ends is vibrating in its 8th harmonic. (a) How many nodes are on the string? (b) The 8th harmonic wavelength is what fraction of the string length? (c) If the 8th harmonic frequency is 976. Hz, what is the frequency of the 2nd overtone? 18. Consider a pipe closed at one end, of length L. a) Draw the wave patterns that correspond to the 3 lowest frequencies that will resonate in this pipe? b) What is the wavelength of the wave, in terms of the length of the pipe L, which corresponds to each wave pattern? c) If the length of the pipe is 18cm and the speed of sound inside the pipe is 350m/s calculate the frequency of the first 3 harmonics for the pipe 19. Explain the difference between constructive and destructive interference? When does each type of behavior occur? 20. Sketch the resultant pattern of the waves shown in the diagram below when they are completely superimposed. Indicate what type of interference is occurring in each case. 21. Based on the picture drawn below, in which medium is the wave traveling faster? Explain your reasoning. Note: the wave is viewed from the top and the black lines represent the peaks of the wave. Medium1 Medium2 2 22. A car horn emits a frequency of 400 Hz. A car traveling at 20.0 m/s sounds the horn as it approaches a stationary pedestrian. What frequency does the pedestrian hear? Assume the speed of sound in air is 343 m/s. Static Electricity Key ideas: -know the properties of electric charge; know the unit for electric charge -know the different ways of charging an object (induction, friction, conduction) -know the difference between conductors and insulators -know the factors that affect the size and direction of electric force -know the equation for Coulomb’s law F = kq1q2/r2 -know the similarities and differences between electric force and gravitational force -know the definition and units of electric field; know that electric field is a vector quantity -know that the direction of an electric field is the same as the direction of the electric force that a positive test charge placed in that field would experience -know the two equations for calculating electric field E = F/q, and E = kQ/r2 -know the definition and properties of electric field lines -know how to draw or identify the electric around a positive/negative point charge and around an electric dipole -know how to identify the sign of the charge causing the electric field based on the direction of the electric field lines Practice Problems 1- What is the SI unit for charge? Is charge a vector or a scalar? What is the smallest possible charge that on object can have? 2- What do the magnitude and direction of the electric force depend on? 3- In what ways is the electric force different from the gravitational force and in what ways is it similar? 4- How many electrons must be added to an electrically neutral silver nickel to give it a charge of 4.8μC? 5- What is the force between two point charges of 7.5 x 10-9 and -3.1 x 10-9 Coulombs when they are separated by a distance of 0.50 meters? 6- What is the magnitude of two identical point charges which are 5.0 m apart when the force between them is 14.4 N? If charge 1 has a mass of 5.0*10-12kg, what is its acceleration? 7- The distance between two charges and is r, and the force between them is F. What is the force between them if the distance between them is tripled? F/4 c. 9F 4F d. F/9 Which of the following is not a property of electric charge? charge is quantized c. charge can be either positive or negative charge is conserved d. charge is a vector a. b. 8a. b. 9a. b. Three rods of different materials A, B, and C, are charged by various methods. When the rods are brought near each other, the rods A and B repel each other, while the rods B and C attract each other. Which of the following statements must be true? A and B have like charges on them c. A and C have like charges on them A and B have equal amounts of charge on them d. A and B have opposite charges on them 10- 3 charges are placed on a meter stick. One charge (q1= +10 μC) is at x1 = 30 cm, the second charge (q2 = +10μC) is at x1= 50.0 cm and the third charge (q3= -8μC) is placed at x3=70cm. (a) Determine the net electric force on charge 1 (magnitude and direction). (b) Determine the net electric force on charge 2 (magnitude and direction) 3 11- A 100-W light bulb is connected to a 110-V supply for 2 minute. How much energy does the light bulb use in 2 minutes? 12- Electric field lines around two charges, A and B, are shown in the diagram below. Based on the picture below determine the sign of charges A and B. 13- Which of the following is NOT true about electric field lines? they are same as the direction of the force exerted on a negative test charge. the density of the lines represents the strength of the electric field they are the same as the direction of the force exerted on a positive test charge. they never cross a. b. c. d. 14- A negative charge of 3.6*10–7 C is placed in an electric field. The charge experiences a force of 7.2 * 10–2 N to the right. What is the magnitude and direction of the electric field at this point? Current Electricity Key ideas: -know the basic elements of a circuit (battery/source, resistor, wires, switch,…) and the role that each element plays in a circuit -know the definitions, units, and symbols for current, resistance, voltage (or potential difference), and electric power -know the equation for how to calculate current using electric charge and time, and be able to apply it in simple problems -know the difference between an Ohmic resistor and a non-Ohmic resistor -know how the length, thickness, and material that a wire is made of affect its resistance -be able to identify the direction of electron flow and the direction of conventional current in a circuit based on a schematic of the circuit -know ohm’s law, V = IR, and know how to apply it to solve simple problems involving current, voltage and resistance - know the 3 equations that can be used to calculate the power used by a resistor or provided by a battery -know how to solve for the energy used by a circuit/resistor using the equation P = E/t -know the differences between a series and parallel circuit and the characteristics of each type of circuit 1- In the circuit shown below, which bulb, when burned out, will cause all other bulbs to stop glowing? a. b. A B c. d. 2- The unit of electric potential difference is a. the Newton b. the Farad C F c. d. The Volt The ampere 3-A 100-W light bulb is connected to a 110-V supply for 2 minute. How much energy does the light bulb use in 2 minutes? 4-Explain the difference between an ohmic and non-ohmic resistor 5- A light bulb, a battery, a ceramic resistor, and an ammeter are all connected in series. The ammeter shows that there is a current through the battery, but the light bulb isn’t lighting up. What is a possible explanation for this? 4
