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P510/2
PHYSICS
PAPER 2
MOCKS 2013
2 ½ HOURS
TURKISH LIGHT ACADEMY
UGANDA ADVANCED CERTIFICATE OF EDUCATION
PHYSICS PAPER TWO
2hours 30minutes
INSTRUCTION TO CANDIDATES
Answer any five questions, including at least one from each section, but not more
than one from either section A or B.
Where necessary assume the following constants:
Acceleration due to gravity,
g
=
9.81ms-2
Speed of light in vacuum,
c
=
3.0 x 108ms-1
Speed of sound in air,
v
Electronic charge,
e
=
Electronic mass,
me
=
9.1x10-31kg
Permeability of free space,
µ0
=
4.0 π x10-7Hm-1
Permittivity of free space,
ε0
=
8.85x10-12Fm-1
The Constant
1⁄4πε0 =
340ms-1
=
1.6 x 10-19C
9.0x109F-1m
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SECTION A
1(a)(i) State the laws of reflection of light.
(2 marks)
(ii) Light is reflected successively, once in each of two mirrors inclined at an
angle β, to each other. Find the deviation produced by the reflections in
terms of β.
(3 marks)
(b) Describe how a sextant can be used determine the angle of elevation of
the sun.
(5 marks)
(c) Describe an experiment to determine the focal length of a concave mirror
using the no-parallax method, including a graphical analysis.
(6 marks)
(d) A concave mirror forms a real image of magnification 3, of an object
placed at point A, in front of it. When the object is moved to point B, a
virtual image of same magnification is obtained. Find the distance AB. (4 marks)
2(a) Derive the expression for the focal length f, of a thin diverging lens in
terms of the object distance u, and the image distance v.
(4 marks)
(b)(i) Define lateral magnification and angular magnification produced by
a lens system.
(2 marks)
(ii) An object is placed a distance x cm from a convex lens of focal length
f cm Find the lateral magnification of the image in terms of x and f. (3 marks)
(c) A concave lens of focal length 30cm is arranged co-axially with a convex lens of
focal length 18cm. An object 3cm tall is placed distance 60cm from the concave lens,
on the side remote from the convex lens. If the lenses are 10cm apart,
(i) find the position of the final image,
(5 marks)
(ii) find the height of the image produced,
(4 marks)
(iii) using a point object draw a sketch ray diagram to show the image formation.
(2 marks)
SECTION B
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(a)
(i)
(ii)
State the principal of surperposition of waves
State Huygen’s construction principal.
(1 mark)
(2 marks)
Use Huygen’s principle to show that for light moving from one
sin i1
medium to another,
= constant. Where i1 and i2 are angles made by the ray in
sin i2
media 1 and 2 respectively, the normal.
(5 marks)
(iii)
(b)(i) What is a diffraction grating?
(1 mark)
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(ii) Sodium light of wave lengths 5.890x10-7m and 5.924x10-7m falls
normally on a diffraction grating of 500lines per cm. Find the angular
deviation between their second order images.
(4 marks)
(d)(i) Describe how interference fringes are formed in Young’s double
slit experiment.
(5 marks)
(ii) State the necessary geometrical conditions for formation of
measurable fringes.
(2 marks)
4. (a)(i) Explain how beats are produced.
(3 marks)
(ii) An observer moving between two identical stationary sources of
sound, along the line joining them, hears beats at the rate of 3.0s-1.
At what velocity is the observer moving if the frequencies of the
sources are 480Hz and the velocity of sound when the observation
was 340ms-1.
(5 marks)
(b)(i) What is meant by resonance?
(1 marks)
(ii) With the aid of a diagram, describe an experiment to investigate
the variation of frequency of a wave in a stretched string with
length of the string.
(6 marks)
(c)(i) With the aid of a suitable diagram, explain the terms fundamental
note and overtone as applied to a vibrating wire fixed at both ends.(3 marks)
(ii) Explain the significance of overtone in production of music?
(2 marks)
SECTION C
5.(a) With the aid of diagram, explain the terms angle of dip and
magnetic meridian, as applied to the earth’s magnetic field.
(4 marks)
(b) Sketch the magnetic field pattern around a vertical straight
current as wire in the earth’s magnetic field.
(2 marks)
(c) Describe, using appropriate circuit diagram, an experiment you
would perform to investigate the variation of the magnetic flux
density at the centre of a circular coil, with the current through
the coil.
(6 marks)
(d) A circular coil of 50 turns and mean radius 0.50m is arranged so
that its plane is perpendicular to the magnetic meridian. The coil
is connected to a ballistic galvanometer of sensitivity 5.7x104rad.C-1.
The total resistance of the coil and the galvanometer is 100Ω. When
the coil is rotated through 1800 about a vertical axis, the ballistic
galvanometer deflects through 0.8 radians.
(i)Calculate the horizontal component of the earth’s magnetic
field intensity.
(5 marks)
(ii)Find the voltage which when applied across a solenoid of
2500 turns per metre and total resistance 5Ω will produce a magnetic
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field at its centre of the same intensity as that calculated in d(i)
above.
6. (a) State the laws of electromagnetic induction.
(3 marks)
(2 marks)
(b) Each turn of a coil of N turns is threaded by a magnetic flux of Ф
webers. The total resistance of the coil is R ohms. Derive the expression
for the charge which circulates through the coil when the magnetic
flux is reduced to zero.
(5 marks)
(c) A coil of 500 turns is wound tightly around the middle of an air cored
solenoid of 1000 turns per metre and mean diameter of 7.0cm. An alternating
current of I = 10Cos20πt amperes is passed through the solenoid.
Calculate the amplitude of the voltage which develops across the terminals
of the coil.
(6 marks)
(d) Explain the following observations:
(i) When a d.c motor is switched on, the initial current decreases to a
steady value when the motor is running at a constant speed.
(2 marks)
(ii)If the motion of a d.c motor is slowed down, the current rises, and
then falls again when it is allowed to run freely again.
(2 marks)
(e) Discuss the factors that determine the maximum emf generated
by a dynamo.
(3 marks)
7. (a) Define root mean square (rms) voltage and reactance of a capacitor. (2 marks)
(b)(i) On the same axes draw graphs to show the variation of voltage across
a capacitor and current in the circuit against time, when a capacitor is
connected to an a.c supply source.
(1 mark)
(ii) Explain why current and voltage in b(i) above are out of phase.
(2 marks)
(ii)Explain the function of a capacitor in a rectifier circuit.
(3 marks)
(c) A flat circular coil of 700 turns, each of radius 15cm, is rotated at a
frequency of 300 revolutions per minute about its diameter, at right angles
to a uniform magnetic field of flux density 0.12T. Calculate the:
(i) maximum magnetic flux linking the coil.
(2 marks)
(ii) emf induced in the coil when the plane of the coil makes angle 300
with the magnetic field.
(3 marks)
(iii) rms value of the emf induced in the coil.
(2 marks)
(d) With the aid of a diagram describe how the repulsion type of ammeter
works.
(5 marks)
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SECTION D
8(a) State Ohm’s law.
(1 mark)
(b) Two resistance wires A and B have resistances in the ratio 4:5; diameters
in the ratio 3:2; and lengths in the ratio 1:2 respectively. When the wires are
connected in series across a voltage source, the current supplied is 0.5A.
Find the
(i) ratio of resistances of the wires.
(3 marks)
(ii) Current supplied to the source when the resistors are connected
in parallel.
(4 marks)
(c)(i) Describe how a potentiometer is used to determine the emf of a cell. (4 marks)
(ii) In the experiment in c(i) above, why is the resistance of the galvanometer
not important?
(1 mark)
(iii) How would the experiment in c(i) above be modified to measure the
internal resistance of a cell.
(4 marks)
(d) A battery of emf 15V and internal resistance 2Ω is connected across
an 8Ω resistor. Calculate the
(i) rate at which electrical energy is being generated in the battery. (2 marks)
(ii) rate of energy dissipation in the resistor.
(1 mark)
9(a)(i) Define electric potential energy of a charge.
(1 mark)
(ii) Derive an expression for the electric potential energy of two point
charges of Q1 and Q2 a distance x apart, in air.
(4 marks)
(b)
Three charges of -5x10-9C, +7x10-9C and +6x10-9C are placed at the vertices
A,B and D respectively of a rectangle, in air. The rectangle is of sides 3cmx5cm
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as in the figure above. Calculate the electric field intensity at C.
(7 marks)
(c)(i) What is an equi-potetial surface?
(1 mark)
(ii) Show that the electric field intensity is always perpendicular to the
equi-potential surface.
(2 marks)
(d) Describe an experiment to show that charge resides only on the outside
surface of a charged hollow conductor.
(5 marks)
10(a)(i) Define the terms: Dielectric constant and dielectric strength.
(2 marks)
(ii) Explain why capacitance changes when a dielectric is placed in a capacitor.
(4 marks)
(iii) List two other uses of dielectric in a capacitor.
(1 mark)
(b) A capacitor with a dielectric of relative permittivity εr, between its plates
is charged then isolated.
(i) Show that when the dielectric is removed from the capacitor, the fractional
change in voltage across its plates is εr -1.
(4 marks)
(ii) If the relative permittivity of the dielectric is 2.3 and the capacitor was
initially charged to 35V find the new voltage across the capacitor.
(2 marks)
(c) The plates of a capacitor of area 4.0cm2 are 3mm apart in air. Find the
(i) charge stored in the capacitor when it is charged to 9000V.
(3 marks)
(ii) energy stored in the capacitor when the area is reduced to half the above
value and the capacitor again charged to the same voltage.
(4 marks)
END
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