Exams › JEE Main › Physics

Two Polaroid sheets are arranged in the path of an unpolarized beam of intensity I0 so that the second sheet transmits no light. If a third Polaroid is inserted between them, and its transmission axis makes an angle θ with the axis of the first Polaroid, what is the intensity of the light emerging from the final Polaroid?

1. (I0 / 8) sin² 2θ
2. (I0 / 4) sin² 2θ
3. (I0 / 8) cos⁴ θ
4. I0 cos⁴ θ

Correct answer: (I0 / 8) sin² 2θ

Solution

After the first sheet intensity is I0/2. The middle sheet (axis at theta) gives (I0/2)cos^2(theta); the last sheet is at 90-theta to it, giving (I0/2)cos^2(theta)*sin^2(theta) = (I0/8)sin^2(2theta).

Related JEE Main Physics questions

• The pupil opening of a human eye is about 2 mm. If the average wavelength of visible light is taken as 5000 Å, the eye’s approximate angular resolving limit is
• For a single-slit diffraction pattern, the condition corresponding to the appearance of secondary maxima is
• In a Fresnel biprism setup, the two lens positions give slit separations of 16 cm and 9 cm. What is the true separation between the slits?
• In a Young’s double-slit setup, two monochromatic sources emit light of wavelengths 2500 Å and 3500 Å. Which pair of fringe orders from the two patterns will fall at the same position?
• In a Young’s double-slit setup, the intensity at a bright fringe maximum is I0. The slit separation is d = 5bb, where bb is the wavelength of the light used. If the screen is placed at a distance D = 10d, what intensity is observed at the point directly opposite one of the slits?
• What is the relationship between the polarizing angle and the critical angle?

⚔️ Practice JEE Main Physics free + battle 1v1 →