Question
A source of plane polarised light is observed through two polarising filters.
The filters are positioned so that the source appears at its brightest. One of the filters is then rotated clockwise and the other filter is rotated anticlockwise through the same angle.
How does the source appear when both filters have been rotated 90° and 180° from their initial positions?
Answer/Explanation
Ans: C
Question
A vertically polarised beam of light of intensity $I_{0}$ is incident normally on a polarising filter.
The transmission axis of the filter is at 45° to the vertical. The beam of light transmitted by this
filter is then incident normally on a second filter. The transmission axis of the second filter is horizontal.
What is the intensity of the beam of light after transmission through the second filter?
(A) $0$
(B)$\frac{1}{4}I_{0} $
(C) $\frac{1}{2}I_{0} $
(D) $I_{0}$
▶️Answer/Explanation
Ans: B
Question
A vertically polarised beam of light is incident normally on a polarising filter. The transmission axis of the filter is at an angle of 40° to the horizontal.
(A) 0.41
(B) 0.59
(C) 0.64
(D) 0.77
▶️Answer/Explanation
Ans: C
Question
A student investigates the polarisation of microwaves. The microwaves from the transmitter are vertically polarised. A metal grille acts as a polarising filter when placed between the microwave transmitter and the receiver. The reading on the voltmeter is proportional to the intensity of microwaves transmitted through the grille. When the transmission axis of the grille is vertical, the voltmeter reads 3.50V
The grille is then rotated through an angle \( \Theta\) . The voltmeter now reads 2.20V. What is \( \Theta \)?
A 37.5°
B 39.0°
C 51.0°
D 52.5°
▶️Answer/Explanation
Ans A