State Examination Commission – Physics Higher Level, 2005
Question 5
(a) A container contains 5.0 kg of water. If the area of the base of the container is 0.5 m2 calculate the pressure at the
base of the container due to the water. (acceleration due to gravity = 9.8 m s–2)
(7)
Pressure = Force/Area = weight of water/area of base of container = (5.0)(9.8)/(0.5)
P = 98 Pa
(b) State Boyle’s law.
(7)
Basic statement
(c) What is the thermometric property of a thermocouple?
(7)
The voltage generated by a metal subjected to a temperature gradient
(d) An object O is placed 30 cm in front of a concave mirror of focal
length 10 cm.
How far from the mirror is the image formed?
(7)
1/u + 1/v = 1/f
1/30 + 1/v = 1/10
1/v = 1/10 - 1/30
1/v = 3/30 – 1/30 = 2/30 = 1/15
v = 15 cm = 0.15 m
(e) A capacitor of capacitance 100 μF is charged to a potential difference of 20 V. What is the energy stored in the
capacitor?
(7)
2
-6
2
E = ½CV = ½(100 × 10 )(20) = 0.02 J
(f) Draw a sketch of the magnetic field due to a long straight current-carrying
conductor.
(7)
(g) A pear-shaped conductor is placed on an insulated stand is shown. Copy
the diagram and show how the charge is distributed over the conductor when
it is positively charged.
(7)
(h) Explain why high voltages are used in the transmission of electrical energy.
(7)
Power is transmitted at high voltages because this results in smaller currents (P = VI) in the transmission
cables, and hence less power losses through the heating effect (P = RI2)
(i) How are electrons produced in an X-ray tube?
(7)
By thermionic emission from a heated filament
(j) Name the fundamental force of nature that holds the nucleus together.
Strong nuclear force
C. Garvey 2005