Advanced level 2025 West catholic mock physics 2
Advanced level 2025 West catholic mock physics 2
Answer all questions
(one hour )
1. Figure 1 shows a circuit made up of two capacitors which can be charged by the battery of 8.0V and
discharged through the series resistors.
Figure 1
The time constant (τ) of the circuit can be defined by
𝜏 = 𝑅𝐶.
Where R represents the total resistance of the circuit and C is the equivalent capacitance of the circuit.
a) Explain the fact that homogeneity of physical equations is not sufficient for the correctness of the
equation.
b) Show that the above equation is homogeneous.
c) Determine the time constant for the above circuit if S2 stays open throughout charging and discharging
process of the capacitors and the charge stored in the capacitors. (7 marks)
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2. The circuit bellow shows resistor and cells connected in a circuit.
Figure 2
Calculate the
a) The currents through each of the resistors are 3.0Ω, 4.0Ω and 9.0Ω.
b) The potential difference between A and B.
c) Distinguish between potential difference and electromotive force. (6marks)
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3. (a) define gravitational potential at a point.
(b) the gravitational potential Ø at a distance r from point mass M is given by the expression.
∅ = –
𝐺𝑀
𝑟
Where G is the gravitational constant.
i) Explain the significance of the negative sign in this expression.
ii) A spherical planet may be assumed to be and isolated point mass with it mass concentrated at the center. A
small mass m is moving near to, a normal to, the surface of the planet. The mass moves away from the planet
through a short distance h, state and explain why the change in the gravitational potential energy ∆𝐸 of the
