A point source emits gamma radiation - AQA - A-Level Physics - Question 28 - 2020 - Paper 2

To determine which graph will show a straight line through the origin, we need to consider the relationship between intensity (I) and distance (d) for a point source of gamma radiation.

According to the inverse square law, the intensity of radiation varies inversely with the square of the distance from the source. This relationship can be expressed as:

I riangleq k rac{1}{d^2}

Where k is a proportionality constant.

To see a linear relationship through the origin, we can rearrange this equation:

$I = k imes d^{-2}$

This indicates that if we plot I against d⁻², we will obtain a straight line. Therefore, the correct answer is:

D I plotted against d⁻²