Edexcel A-Level Physics A2 C 3 3 Linear Relationships Questions

Review linear relationships in Edexcel A-Level Physics through y = mx + c comparisons, graph validity checks and constant-gradient arguments.

Exam points

rearrange a physical equation into y = mx + c form to justify a straight-line graph

[Maximum number: 2]

The absorption of beta particles in aluminium can be investigated using the apparatus shown.

Figure for Question Edexcel A-Level Physics A2 C 3 3 Linear Relationships Questions question 1 — Edexcel A-Level Physics A2

A student planned to test whether beta particles are absorbed by aluminium according to $C=C_0e^{-\mu x},$ where C is the count rate through thickness x, $C_0$ is the count rate with no aluminium, and $\mu$ is a constant.

Explain why a graph of $\ln C$ against x could be used to test the validity of this relationship.

Taking logarithms gives $\ln C=\ln C_0-\mu x.$ This has the form y=c+mx, so the graph should be a straight line with constant gradient $-\mu$ .

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Edexcel A-Level Physics A2 C 3 3 Linear Relationships Questions question 1