Two beams, A and B , of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position where the beam A has maximum intensity and the other beam B has zero intensity, the polaroid is rotated through 30° making the two beams appear equally bright. If the initial intensities of the two beams are IA and IB respectively, then (IA/IB) equals

Question

Two beams, A and B , of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position where the beam A has maximum intensity and the other beam B has zero intensity, the polaroid is rotated through 30° making the two beams appear equally bright. If the initial intensities of the two beams are IA and IB respectively, then (IA/IB) equals (A) 2 (B) 3/2 (C) 1 (D) 1/3

Tardigrade Admin · Accepted Answer

IAcos230° =IBcos260° ⇒ (IA/IB)=(1/3)

$2$

$3/2$

$1$

$1/3$

$I_{A} co s^{2} 3 0^{\circ} = I_{B} co s^{2} 6 0^{\circ}$
$\Rightarrow \frac{I _{A}}{I _{B}} = \frac{1}{3}$

2

3/2

1

1/3

IA​cos230∘=IB​cos260∘ ⇒IB​IA​​=31​

$2$

$3/2$

$1$

$1/3$

$I_{A} co s^{2} 3 0^{\circ} = I_{B} co s^{2} 6 0^{\circ}$
$\Rightarrow \frac{I _{A}}{I _{B}} = \frac{1}{3}$