MJ22 P52 Q2 Cepheid Luminosity

9702/52/M/J/22: The brightness of some stars varies regularly. These stars are called variable stars. Fig. 2.1 shows the variation of luminosity with time for a variable star. A student determines the period T and mean luminosity L of the star. The student repeats the process for different variable stars.

It is suggested that L and T are related by the equation \(L = SKT^a\) where S is the luminosity of the Sun, and a and K are constants.

Sample solutions for practical Paper 5 variant 2 Question 2 May/June 2022 Cambridge A Level Physics.

MJ22 P52 Q1 Magnetic Launcher "Rail Gun" Metal Bar

9702/52/M/J/22: Two parallel cylindrical conductors each have a small cross‑sectional area A. A thin metal bar connects the two conductors, as shown in Fig. 1.1. The metal bar has a square cross‑section with sides of length y. For each conductor, the distance between its end C and the centre of the metal bar is L. The distance between the centres of the conductors is x.

The ends C are connected to a power supply and the current I in the conductors is measured.

It is suggested that I is related to L by the relationship

\(\dfrac{e}{I} = \dfrac{2PL}{A} + \dfrac{Qx}{y^2} \)

where E is the electromotive force (e.m.f.) of the power supply, and P and Q are constants.

Plan a laboratory experiment to test the relationship between I and L. Draw a diagram showing the arrangement of your equipment. Explain how the results could be used to determine values for P and Q.

Sample work sheet for planning before actually writing the solutions on the lines:

Sample solutions for practical Paper 5 variant 2 Question 1 May/June 2022 Cambridge A Level Physics.