Polarisation, Brewster's law and Polaroids — NEET & JEE Questions

Question 1 · difficulty L1 · recall

Polarisation demonstrates that light is

• A. transverse
• B. longitudinal only
• C. a scalar with no field direction
• D. unable to interfere

Question 2 · difficulty L1 · understanding

Unpolarised light passing through an ideal polariser emerges

• A. unpolarised with identical directional distribution
• B. plane-polarised
• C. longitudinal
• D. with zero intensity always

Question 3 · difficulty L2 · understanding

An unpolarized light of intensity $I_0$ passes through polarizer and then through a certain optically active solution and finally it goes to analyser. If the angle between analyser and polariser is $0^{\circ}$ and intensity of light emerged from analyser is $\frac{3}{8} I_0$, the angle of rotation of the light by the solution with respect to analyser is $\_\_\_\_$ degrees.

Question 4 · difficulty L2 · understanding

An unpolarised light beam is incident on the polarizer of a polarization experiment and the intensity of light beam emerging from the analyzer is measured as 100 Lumens. Now, if the analyzer is rotated around the horizontal axis (direction of light) by 30$$^\circ$$ in clockwise direction, the intensity of emerging light will be _________ Lumens.

Question 5 · difficulty L2 · understanding

When an unpolarized light falls at a particular angle on a glass plate (placed in air), it is observed that the reflected beam is linearly polarized. The angle of refracted beam with respect to the normal is $\_\_\_\_$ . $\left(\tan ^{-1}(1.52)=57.7^{\circ}\right.$, refractive indices of air and glass are 1.00 and 1.52, respectively.)

• A. $36.3^{\circ}$
• B. $39.6^{\circ}$
• C. $42.6^{\circ}$
• D. $32.3^{\circ}$

Question 6 · difficulty L2 · understanding

Two plane polarized light waves combine at a certain point whose electric field components are $$\begin{aligned} & E_1=E_0 \operatorname{Sin} \omega t \\ & E_2=E_0 \operatorname{Sin}\left(\omega t+\frac{\pi}{3}\right) \end{aligned}$$ Find the amplitude of the resultant wave.

• A. $1.7 \mathrm{~E}_0$
• B. $\mathrm{E}_0$
• C. $0.9 \mathrm{~E}_0$
• D. $3.4 \mathrm{~E}_0$

Question 7 · difficulty L2 · understanding

When unpolarized light is incident at an angle of $$60^{\circ}$$ on a transparent medium from air, the reflected ray is completely polarized. The angle of refraction in the medium is:

• A. $$60^{\circ}$$
• B. $$90^{\circ}$$
• C. $$30^{\circ}$$
• D. $$45^{\circ}$$

Question 8 · difficulty L2 · understanding

A beam of unpolarised light of intensity $$I_0$$ is passed through a polaroid $$A$$ and then through another polaroid $$B$$ which is oriented so that its principal plane makes an angle of $$45^{\circ}$$ relative to that of $$A$$. The intensity of emergent light is:

• A. $$I_0 / 2$$
• B. $$I_0 / 8$$
• C. $$I_0 / 4$$
• D. $$I_0$$

Question 9 · difficulty L2 · understanding

An unpolarised light beam of intensity $$2 I_{0}$$ is passed through a polaroid P and then through another polaroid Q which is oriented in such a way that its passing axis makes an angle of $$30^{\circ}$$ relative to that of P. The intensity of the emergent light is

• A. $$\frac{\mathrm{I}_{0}}{4}$$
• B. $$\frac{\mathrm{I}_{0}}{2}$$
• C. $$\frac{3 I_{0}}{4}$$
• D. $$\frac{3 \mathrm{I}_{0}}{2}$$

Question 10 · difficulty L2 · understanding

In the List-I, four optical effects are mentioned. The physical phenomena of light which are essential to describe these optical effects are given in List-II. Choose the option which describes the correct match between the entries in List-I to those in List-II. List-I List-II (P) Colorful sky in north polar region (Aurora Borealis) (1) Dispersion and reflection (Q) Partially polarized sun light (2) Total internal reflection (R) Rainbow (3) Diffraction (S) Dark and bright fringes (4) Scattering of light by molecules in the atmosphere (5) Emission of radiation from oxygen and nitrogen atoms excited by charged particles

• A. P→5, Q→4, R→1, S→3
• B. P→4, Q→2, R→1, S→3
• C. P→4, Q→1, R→2, S→3
• D. P→5, Q→4, R→1, S→2