Friday, August 17, 2018
CAMEROON GCE ORDINARY LEVEL PHYSICS 2018 PAPER 2 ANSWERS
Friday, November 20, 2015
GCE Advanced level Physics questions on SIMPLE HARMONIC MOTION ELECTROMAGNETIC INDUCTION NUCLEAR PHYSICS QUANTUM PHYSICS GRAVITATIONAL FIELD ELECTRIC FIELDS
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| GCE Advanced level Physics questions on
SIMPLE HARMONIC MOTION
ELECTROMAGNETIC INDUCTION
NUCLEAR
PHYSICS
QUANTUM PHYSICS
GRAVITATIONAL FIELD
ELECTRIC
FIELDS
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SIMPLE
HARMONIC MOTION
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1.
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a.
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(i)
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Explain what
is meant by simple harmonic motion
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(2marks)
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(ii)
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Sketch graphs
showing how the following quantities vary with the period of oscillation for
one complete cycle.
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Kinetic energy
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Potential energy
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Total energy
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(5marks)
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b.
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A pendulum
bob of length 1.2m has a bob of mass 0.2g. The bob is pulled aside a horizontal
distance of 20.0cm and then released.
Calculate
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(i)
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The velocity
of the bob at its lowest point.
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(3marks)
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(ii)
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The maximum
kinetic energy of the bob.
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(2marks)
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c.
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Mechanical
systems may undergo free, damped and forced oscillations.
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Explain the
meaning of the underlined words
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(3marks)
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d.
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The
displacement x in m, form the equilibrium position of a particle moving with
SHM is given by
 Where t
the time measured in s, and measured from an instant when x=0. |
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(i)
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State the
amplitude of the oscillation
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(1marks)
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(ii)
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Calculate the
time period of the oscillations
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(2marks)
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(iii)
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The maximum
acceleration of the particle.
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(2marks)
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OR
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ELECTROMAGNETIC
INDUCTION
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e.
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(i)
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State the laws of electromagnetic induction
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(4marks)
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(ii)
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Define electromagnetic induction
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(2marks)
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(iii)
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Explain the origin of the back emf in an electric
motor
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(3marks)
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The flux density between the poles of a powerful
electromagnet is 2.5T. what is the force exerted on 15mm of wire carrying a
current of 3.0A when the wire is
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f.
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(i)
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At right angles to the field
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(2marks)
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(ii)
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Parallel to the field
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(1marks)
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(iii)
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At an angle of 30o to the field
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(2marks)
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g.
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A coil of L = 30mH and a resistance R = 5Ω is
connected in series with a capacitor C. An a.c supply connected across them
gives 12V rms at 40Hz
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(i)
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Calculate the value of C at resonance
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(2marks)
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(ii)
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Calculate the rms current at resonance
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(2marks)
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(iii)
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Calculate the rms pd across the coils at resonance
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(2marks)
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Answer
either 2 (a),(b),(c) and (d) or 2(e),
(f) (g)
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NUCLEAR PHYSICS
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2.
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a.
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(i)
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State the observations obtained from the Rutherford alpha
scattering experiment with a thin metal foil.
What conclusions may be deducted from each of these
observations
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(6marks)
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(ii)
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Explain how and why the masses of compound differ
from the sum of the masses constituent particles
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(2marks)
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b.
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Radium (Ra) decays to radon (Rn) by the reaction
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(i)
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Estimate the energy released in joules when an atom
of Ra decays
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(ii)
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Estimate the wavelength of gamma photon emitted
during this decay given that 4% of the energy released turns to gamma
radiation
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(iii)
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What happens to the remaining 96% of the energy
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The atomic masses of radium = 3.753 x 10-25kg,
radon = 3.686 x 10-25kg , helium = 0.066 x 10-25kg
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(8marks)
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c.
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An alpha – particle is accelerated to attain a
kinetic energy of 1.34 x 10-15kJ collides head on with a gold
nucleus. Calculate the upper limit of the radius of gold nucleus. (the proton number of gold is 79)
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(4marks)
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Planck
constant
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OR
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QUANTUM PHYSICS
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d.
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Electrons can be emitted from the surface of zinc by
ultra violet light nut by visible light. On the other hand, electrons can be
emitted from potassium even by visible light.
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(i)
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Explain why visible light cannot cause electrons to
be emitted from the surface of zinc whereas ultraviolet light.
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(2marks)
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(ii)
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If both metals were illuminated with ultraviolet
light of the same frequency, how will the energies of electrons emitted from the
zinc and potassium surface differ
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(2marks)
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e.
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Explain each of the following
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(i)
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If the intensity of the violet light directed at a
piece of zinc is double, the number of electrons leaving the surface per
second also doubles but the maximum kinetic energy is uncharged.
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(4marks)
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(ii)
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The maximum kinetic energy of photoelectrons is
directly proportional to the difference between the frequency of light
falling on the surface and the threshold frequency for that metal
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(4marks)
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(iii)
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Gamma photons are more harmful to people than
infrared photons
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(3marks)
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f.
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Calculate the wavelength of the photon emitted when
an electron makes a quantum jump from the n= 3 state to the ground state of
the hydrogen atom. The energy state of the state n=3 is -1.52eV and that at
the ground state is 13.6eV.
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(5marks)
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Choose one
question from either question 3, 4 or 5
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ENERGETICS
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3.
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a.
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(i)
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Distinguish between specific (latent) heat of
vaporization and latent heat of vaporization.
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(4marks)
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(ii)
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Describe and experiment to determine the specific
latent heat of vaporization of water
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(7marks)
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b.
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An electric heater rated at 2.0W is used to heat 15g
of water in a copper kettle. The initial temperature of the water is 20oC.
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(i)
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What time does it take to heat the water to its
boiling point
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(3marks)
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(ii)
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Calculate the mass of water that would have boiled
away in five minutes
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(3marks)
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c.
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Estimate how long it would take all the water to
evaporate. State any assumptions that you make in your calculations.
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(3marks)
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Specific heat capacity of water is 4200Jkg-1K-1
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Heat capacity of copper is 400 JK-1
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GRAVITATIONAL FIELD
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4.
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a.
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(i)
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State Newton’s law of gravitation
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(2marks)
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(ii)
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State Kepler’s laws of planetary movement
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(3marks)
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(iii)
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Determine the dimension of the universal gravitation
constant G
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(2marks)
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b.
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Derive an expression for the acceleration g, due to
gravity at the earth’s surface in terms of G, the radius of the earth R and
its density,
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(4marks)
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c.
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Calculate the escape velocity of the earth given
that
Radius of
earth, R = 6.4 x 106m,
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(3marks)
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d.
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A communication satellite revolves round the earth
in a circular orbit at a height of 36000km above the earth’s surface. Fine
the satellite’s period of revolution in hours. Comment on the results.
Radius of
earth, R = 6.4 x 106m, G =6.7x10-11 Nm2kg-2
,mass of the earth M =
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(7marks)
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ELECTRIC
FIELDS
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5.
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a.
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(i)
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State coulomb’s law
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(2marks)
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(ii)
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The variation of the force (F/N) between a pair of
equally charged molecules in a medium with the inverse square of the distance
r them is shown in the graph below
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Fig 1
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Fig 2
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Use the graph to obtain a value for the permittivity
of the medium, given that each charge is 4x10-3C
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(4marks)
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b.
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Sketch separate graphs showing the how the electric
field strength E and electric
potential V varies with distance r, from the Centre of a uniform solid metal
sphere of radius ro which is positively charged.
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(4marks)
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c.
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A 10uF capacitor is charged from a 30V supply and
then connected across an uncharged 50uF capacitor as shown on fig 2.
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(i)
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What is a capacitor
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(1marks)
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Calculate the
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(ii)
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The initial charge stored on the 10uF capacitor
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(1marks)
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(iii)
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The final p.d across each capacitor
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(1marks)
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(iv)
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The final charge on each capacitor
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(1marks)
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