A strip of plane mirror 40 mm in length lies horizontally with one end resting on a fixed support and the other on top of a vertical rod.
A beam of light is reflected from the mirror and forms a spot on a screen 2.0 m above the mirror.
a)If the vertical rod is moved 1 mm upwards, how far does the spot of light on the screen move? Answer: 100 mm
b)If the smallest movement of the spot of light that can be observed is 1 mm,what is the smallest movement of rod which can be recorded? Answer: 0.01 mm
我有試下計架,計到佢rotate緊個mirror with angle theta = tan-1 (1/40) ,所以rotate 完, new incident angle 和 reflected angle 都會減theta?
但之後唔識計,有冇高人可以幫幫手指點下
,thank you very much
