Two linear polarisers are placed coaxially. T | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(A) Since the beam incident on the first polariser is unpolarised,its intensity is reduced to half upon passing through the first polariser. Malus' la

Vedclass · Accepted Answer

$I_{1}=10.0 \,W/m^{2}$ and $I_{2}=7.5 \,W/m^{2}$

Vedclass · Answer

(A) Since the beam incident on the first polariser is unpolarised,its intensity is reduced to half upon passing through the first polariser. Malus' law is not applicable here.Therefore,the intensity $I_{1}$ after the first polariser is:$I_{1} = \frac{I_{0}}{2} = \frac{20}{2} = 10 \,W/m^{2}$As the light emerging from the first polariser is linearly polarised,Malus' law is applicable for the second polariser.The intensity $I_{2}$ obtained after the second polariser is given by:$I_{2} = I_{1} \cdot \cos^{2} 	heta$where $	heta$ is the angle between the transmission axes of the first and second polarisers.Given the angles are $30^{\circ}$ and $60^{\circ}$ from the vertical,the angle between them is $	heta = 60^{\circ} - 30^{\circ} = 30^{\circ}$.Thus,$I_{2} = 10 	imes \cos^{2} 30^{\circ}$$I_{2} = 10 	imes \left(\frac{\sqrt{3}}{2}ight)^{2} = 10 	imes \frac{3}{4} = 7.5 \,W/m^{2}$

Similar Questions

An unpolarized light passes through three polarizing sheets whose polarizing directions make an angle of $30^o$,$60^o$,and $30^o$ with the $y$-axis in the same sense. What fraction of the initial intensity is transmitted by the system?

Explain Malus's law and state its mathematical expression.

Unpolarised light falls on two polarizing sheets placed one on top of the other. What must be the angle between the characteristic directions of the sheets if the intensity of the final transmitted light is one-third the maximum intensity of the first transmitted beam?

The relation $I = I_0 \cos^2 \theta$ is known as (where $I_0$ is the intensity of incident light on the analyser,$I$ is the intensity of emergent light from the analyser,and $\theta$ is the angle between the plane of polarization and the axis of the analyser):

An unpolarized light beam of intensity $I_0$ is passed through a first polaroid $A$ and then through a second polaroid $B$. If the principal plane of polaroid $B$ makes an angle of $45^{\circ}$ with that of $A$,find the intensity of the emerging light.

Vedclass Test Series

Exam Paper Generator

Online Exam Module