In an experiment to investigate the relationship between light intensity $I$ lux on a surface and

Question

In an experiment to investigate the relationship between light intensity $I$ lux on a surface and distance $d$ metres from a light source, a student obtained the following results. One of the values of $I$ is incorrect. $d$ (metres)$2$$5$$10$$20$$30$ $I$ (lux)$875$$141$$35$$4.22$$3.89$ It is known that $I$ and $d$ are related by the equation $I = Ad^n$, where $A$ and $n$ are constants. Plot $\lg I$ against $\lg d$ and draw a straight line graph.[3] Use your graph to identify the incorrect reading of $I$ and estimate its correct value,[3] estimate the value of A and of n.[4] Using the tables of values, explain, with working, how the light intensity I changes when the distance d from the light source is doubled.[1]

Accepted Answer

(b)(i)incorrect *I* = 4.22, corrected *I* = 8.91 (b)(ii)A=3980, n =- 2.04

2025 SJI PRELIMS P2 Q7

2025 SJI PRELIMS P2 Q7