Q was - The student wishes to measure the height of the image on the screen in order to check
his result. However he finds that when he tries to do this his hand and the rule prevent
the light reaching the screen. Suggest briefly a method he could use to measure the
height of the image on the screen that would overcome this problem.
AND This Was the Answer as on the marksheet:
scale drawn on paper on screen/graph paper on screen/
mark on screen (then) measure/clamp ruler on scale/
use translucent screen and measure from other side