An incident ray is reflected normally by a plane mirror onto a screen where it forms a bright spot. The mirror and screen are parallel and 1m apart. If the mirror is rotated through 5º, calculate the displacement of the spot
A
8.7cm
B
10.0cm
C
15.4cm
D
17.6cm
Verified Correct Answer: D.
Physical Principles & Numerical Solution
From the diagram above,
Tan\(\theta\) = \(\frac{\text{d}}{100}\)
Tan10º = \(\frac{\text{d}}{100}\)
d = 100 x Tan 10º = 100 x 0.1763 ≈ 17.6cm.
Source: Myschool Past Questions Archive (Record #33909)