A physicist investigates how light intensity varies with distance from a light bulb. He
sets up the apparatus as shown.
Mark on the diagram the exact distance d he should measure.
State why the resistance R of the LDR will increase as it gets further away from the
State the most important quantity to control to ensure a fair test and explain how the
physicist might control it.
The relationship between R and d is given by
where k and p are constants.
Explain why a graph of ln R against ln d will give a straight line.
He measures R for different values of d and records the following results.
Plot a graph of ln R against ln d. Use the column(s) provided to show any processed
Use your graph to find a value for p.
Use your graph to find a value for k.