S.6 Physics Seminar
S.6 Physics Seminar
S.6 Physics Seminar
S,
NAMUGONGO ON 24TH SEPTEMBER 2022
P510/1 & P510 /2
PHYSICS PAPER 1 & 2
SECTION A
1. (a) (i) Define the following angular velocity and centripetal
acceleration. [2]
(ii) Derive the expression for the acceleration of a body moving
with angular velocity ω through a circular path of radius r.
[4]
(b) (i) What is meant by banking of a road in circular motion? [1]
(ii) Draw a sketch diagram to show forces acting on a car moving
round a banked track. [2]
(iii) A car moves along a circular track of radius 100 m, banked
at an angle of 10°. If the coefficient of friction between the
tires of the car and the ground is 0.3, find the maximum
speed at which the car can move without overturning. [4]
(c) A conical pendulum has a string of length 1.2 m and describes a
horizontal circular path of radius 0.6 m. If the tension in the string
is 22.66 N, find the;
(i) Mass of the body attached to the string [3]
(ii) Angular speed of the mass. [2]
(d) Explain why a motor cyclist leans towards the centre of a circular
path. [2]
[Mt. St. Mary’s College Namagunga]
120°
Q
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SECTION B
7. (a) (i) Define a thermometric property. [1]
(ii) Explain why different thermometers give different values for
temperature of a body. [2]
(b) With use of a labeled diagram, describe how a constant-volume
thermometer is used to determine absolute temperature of a body.
[6]
(i) Draw and label a P-V diagram for the above processes. [2]
11. (a) (i) Define molar heat capacity of a gas at constant pressure
Cp and state its units. [2]
(ii) 750 J of heat is suddenly released into the gas and its
pressure rises to 1.8×105 Pa. Assuming no heat is taken up
by the vessel, calculate the temperature rise and the specific
heat capacity of the gas at constant volume. [4]
(c) Explain why the pressure of a gas increases when the gas is heated
at constant volume. [2]
(d) One mole of an ideal gas is initially at a pressure of 1.0×105Pa and
temperature 25ᵒC. It undergoes a reversible adiabatic expansion to
twice its volume followed by a reversible isothermal compression to
its original volume.
(i) Draw a P-V sketch graph to show the two processes. [2]
(ii) Calculate the final temperature and pressure of the gas. [4]
(Ratio of molar Heat Capacities of the gas is1.4)
[St. Henry’s college Kitovu]
(ii) Find the electric field intensity that can be applied vertically
to move the drop with velocity 0.005ms-1 upwards. [3]
[Density of air = 1.29 kgm ; coefficient of viscosity of
-3
14. (a) Define the following terms as used in the study of radioactivity.
(i) Activity (ii) Decay constant (iii) Atomic Mass Unit.
[3]
(b) (i) Sketch a graph showing how binding energy per nucleon
varies with mass number. [1]
(ii) Describe the main features of the graph in b (i) above. [3]
54
Fe
(c) A fresh sample of radioactive 26 , weighs 15g, and its activity is
8.5 × 1014 disintegrations per second. Find the:
54
Fe
(i) Half-life of 26 . [4]
(ii) The activity of 15g sample after two years [3]
(i) Calculate the ionisation energy for the hydrogen atom. [1]
(ii) Calculate the wave length of the radiation emitted by the
electron transition from the 4th to 2nd energy level. [2]
[Uganda Martyrs S.S.S. Namugongo]
15. (a) (i) With the aid of a diagram describe how cathode rays are
produced. [4]
(ii) Explain how the sign of the charge of cathode rays may be
determined. [2]
(b) An electron is projected with a speed of 3.0 x 10 ms in the
7 -1
2. (a) (i) With aid of ray diagrams distinguish between chromatic and
spherical aberration. [3]
(ii) Distinguish between a microscope and a telescope. [2]
(b) (i) Draw a ray diagram to show how the final image is formed by
a compound microscope in normal adjustment. [3]
(ii) Derive the expression for magnification produced by a
microscope in normal adjustment. [4]
(iii) State one limitation of the microscope in normal adjustment.
[1]
(c) A microscope consists of an objective lens of focal length 6cm and
an eyepiece of focal length 10cm. The final virtual image of an
object placed 8cm from the objective is formed 30cm from the
eyepiece. Calculate the;
SECTION B
4. (a) (i) Define a wave front. [1]
(ii) State Huygens’s construction principle. [1]
(iii) Use Huygens’s principle to show that for light travelling from
one medium to another,
sin i1
sin i2 = c1
c2 , where c1 and c2 are the
respective speeds in the media. [5]
(b) (i) What is meant by Doppler's effect? [1]
(ii) Explain how Doppler’s effect is applied in the traffic radar
speed gun. [5]
(c) (i) An observer standing by the road hears sound of frequency
600HZ coming from the horn of an approaching car. When
the car passes, the frequency appears to change to 560HZ.
Given that the speed of sound in air is 320ms-1, calculate the
speed of the car. [4]
(ii) A radar speed gun emitting radio waves of frequency 10GHz
is directed toward an approaching vehicle. The gun registers
beats at the rate of 0.6Hz. Find speed of the vehicle. [3]
[Seeta High School, Main Campus]
SECTION C:
7. (a) Define electromagnetic induction. [1]
(b) With the aid of a diagram describe how a simple d.c motor works.[6]
(c) A motor with 600 turns coil of area 0.4m2 and resistance of 50Ω
rotates in a radial magnetic field of flux density 2×10-4T. The motor
draws a current of 0.8A when connected to 240V upply. Find the;
(i) angular speed of the coil. [4]
(ii) efficiency of the motor. [3]
(d) Derive an expression for the charge 𝑄which flows through a coil of
resistance R when the magnetic flux linking the coil changes from
𝝓𝟎 to 𝝓𝒇 . [6]
[Namilyango College]
11 UACE PHYSICS SEMINAR 2022 @UMSSN
8. (a) (i) Distinguish between mutual and self-induction. [2]
(ii) Define self inductance. [1]
(b) (i) Describe the construction and operation of the a.c.
transformer. [6]
(ii) Explain why increase in the secondary current leads to an
increase in the primary current. [4]
(c) A transformer designed to step down voltage to 12V is 90% efficient.
It has 3000 turns in the primary and 150 turns in the secondary.
Find amplitude of primary current when the load connected to the
secondary takes power of 30W. [4]
(d) Give three advantages of a.c. over d.c. in power production and
transmission. [3]
[Uganda Martyrs S.S.S. Namugongo]
9. (a) Define the terms;
(i) Impedance. [1]
(ii) Reactance. [1]
(b) A coil of wire of inductance 0.04VA s is connected to sinusoidal
-1
current, I = 5sin120t.
(i) Find the instantaneous back e.m.f. in the coil. [3]
(ii) Find the r.m.s. value of the voltage. [2]
(c) (i) Derive the expression for resonant frequency when an
inductor of inductance L , a capacitor of capacitance C and
the resistor of resistance R are connected in series to an ac
source of variable frequency. [4]
(ii) Varying current I flows in a solenoid of length x, N turns and
cross section area A. Show that back emf induced in the
𝑑𝐼 µ𝑁 2 𝐴
solenoid is 𝐸 = −𝐿 𝑑𝑡, where 𝐿 = . [3]
𝑥
(d) A coil of zero resistance and self inductance 5.0H is connected to a
1000 resistor and an oscillator whose output voltage is 400V
(r.m.s) at a frequency of 63. 7Hz. Find,
(i) r.m.s value of the current flowing through the circuit. [3]
(ii) p.d across the coil [3]
[Mt. St. Mary’s College Namagunga]
10. (a) (i) Define the root mean square value of an alternating current.
[1]
(ii) Derive the relationship between the root mean square value
and the peak value of an alternating current. [5]
(b) A 600Ω resistor, a 5µF capacitor and a 0.8H inductor are connected
in series to an alternating voltage supply of 𝑉 = 340𝑠𝑖𝑛50𝜋𝑡.
(i) Determine the root mean square value of the alternating
current flowing through the circuit. [5]
(ii) Sketch on the same axes the variation of impedance,
capacitive reactance and inductive reactance with frequency
of the alternating voltage. [2]
(c) (i) Describe the action of a hot wire meter. [5]
SECTION D
11. (a) Define the terms:
(i) Electric field intensity at a point in an electric field. [1]
(ii) Electric field potential at a point in an electric field. [1]
(b) Two small identical charged spheres of mass 8g each carrying
similar charges each are hanged from the same point on insulating
threads of length 20cm each. When the spheres settle they are 4cm
from each other.
(d)
15. (a) (i) Distinguish between potential difference and e.m.f. [2]
(ii) Explain why terminal p.d across a cell is not always equal to
the e.m.f? [3]
(b) Show that maximum power is produced in a circuit when its load
resistance is equal to internal resistance of the battery to which it is
connected. [4]
(c) Describe how you would use a potentiometer to calibrate a
voltmeter. [5]
(d) In the circuit shown, D is a driver cell of negligible internal
resistance. AB is a uniform slide wire of resistance 20. S is a
standard resistor of 5. E is a cell of e.m.f. 1.5V. R is a resistor of
10.
When both switches are open balance length is 20 cm. When only
K2 is closed the balance length is 15 cm.
(i) Calculate the internal resistance of E. [3]
(ii) Calculate the balance length when both K1 and K2 are closed.
[3]
[Mt. St. Mary’s College Namagunga
END