Measure the distance x on Fig. 3.1 and record it.
Fig. 3.1 is drawn at one fifth of full size. Use your answer to (a)(i) to work out the actual object distance u from the lens.
Deduce the image distance v, meaning the distance from the lens to the screen when a clear image is formed.
Describe two ways in which the illuminated object and its image on the screen are different.
Transfer your u values and v values from (a)(ii) and (a)(iii) into Table 3.1. Complete Table 3.1 by finding the value of (u × v) for each value of D. Give your answers to 3 significant figures.
Use the grid in Fig. 3.4 to draw a graph of (u × v)/cm^2 on the y-axis against D/cm on the x-axis. Add the straight line of best fit.
The focal length $f$ of the lens has the same numerical value as the gradient of the line. Calculate the gradient of the line. Show all working and indicate on your graph the values you use.
The lens manufacturer says that the focal length of the lens is $15.0\,\text{cm} \pm 10\%$. Decide, with a calculation, whether your value of $f$ agrees with this statement and tick the box that shows your answer.