Assertion (A): When a monochromatic light beam is incident normally on a reflective surface, under some condition it is possible that all lights is transmitted without any reflection.
Reason (R): When light after passing through a polaroid is incident on a reflecting surface at angle of incidence equals to polarizing angle, then all light gets transmitted without any reflection.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is false. Total transmission at normal incidence on a reflective surface is only possible if the refractive indices are identical, implying no actual reflection.
Reason (R) is false. At Brewster's angle, only the p-polarized component of light is completely transmitted. If the light passed by the polaroid is s-polarized, it would be reflected. Therefore, the statement 'all light gets transmitted' is not universally true for light passed by a polaroid without specifying its polarization.
Thus, both (A) and (R) are false.
Assertion (A): Two persons separated by a \(7\text{ m}\) partition wall in a room of \(10\text{ m}\) high can heard each other easily but cannot see each other.
Reason (R): Any sound wave can bend by the obstacle while light can’t.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true. This is a common observation due to the differing wavelengths of sound and light.
Reason (R) is true. Sound waves have longer wavelengths than light waves, causing them to diffract (bend) significantly around common obstacles. Light waves also diffract, but negligibly so for large obstacles like walls.
Reason (R) correctly explains Assertion (A).
Assertion (A): The fringe pattern in Young’s double slit experiment is result of both phenomena of interference and diffraction.
Reason (R): Diffraction results from superposition of wavelets of same wavefront.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true. The YDSE pattern is an interference pattern modulated by the diffraction pattern from each individual slit.
Reason (R) is true. Diffraction is explained by Huygens' principle, where secondary wavelets from the same wavefront superpose.
Reason (R) defines diffraction but does not explain why both interference and diffraction contribute to the YDSE pattern, so it's not the correct explanation.
Assertion (A): Wave nature can be proved by phenomena of interference and diffraction.
Reason (R): Only transverse wave can show the phenomena of polarization.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true. Interference and diffraction are characteristic wave phenomena, providing strong evidence for the wave nature of light.
Reason (R) is true. Polarization is a property exclusive to transverse waves, where oscillations are perpendicular to the propagation direction.
Reason (R) describes a unique property of transverse waves, which is distinct from demonstrating wave nature via interference/diffraction. Thus, (R) does not explain (A).
Assertion (A): Huygens’s principle can explain converging nature of convex lens.
Reason (R): Snell’s law can be derived from Huygens’s principle.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true. Huygens' principle, through its explanation of wavefront changes, can explain how a convex lens converges light.
Reason (R) is true. Snell's law of refraction, which governs how light behaves at interfaces, can be derived directly from Huygens' principle.
Reason (R) explains a fundamental principle (Snell's Law) that underpins the behavior of lenses, thus it correctly explains (A).
Assertion (A): In a YDSE, the two slits are at distance ‘a’ apart. Interference pattern is observed on a screen at a distance D from the slits. At a point on the screen which is directly opposite to the slit, a dark fringe is observed. Then the wavelength of wave is proportional to square of distance between slits.
Reason (R): The light ray coming from two slits do not interfere at the screen.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true. If a dark fringe occurs at \(y = a/2\) (point opposite one slit), the path difference is \(a^2/(2D)\). For a dark fringe, \(a^2/(2D) = (n + 1/2)\lambda\), implying \(lambda \propto a^2\).
Reason (R) is false. The core principle of YDSE is the interference of light waves from two coherent slits, which produces the observed pattern on the screen.
Assertion (A): In a Young’s double slit experiment if slit separation is slightly greater than (nl) if (n) is integer No. of maxima on screen is (2n + 1) & no of minima is (2n).
Reason (R): In Young’s double slit experiment path difference at different position are different.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true. If slit separation (d) is slightly greater than (nlambda), there will be (2n+1) maxima and (2n) minima. Reason (R) is also true as path difference (Delta x = d sintheta) varies with position. However, (R) does not explain the specific count of fringes in (A).
Assertion (A): In standard YDSE experiment if upper slit is slightly moved downward then central maxima shifts downward.
Reason (R): Fringe width in such case will increase.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true; moving a slit shifts the central maxima in the direction of the movement. Reason (R) is false. Fringe width \(\beta = \frac{\lambda D}{d}\) depends on wavelength, screen distance, and slit separation, none of which change.
Assertion (A): If the phase difference between the light waves emerging from the slits of the Young’s experiment is \(\pi\) radian, then central fringe will be dark.
Reason (R): Phase difference is equal to \(\frac{2\pi}{\lambda}\) times the effective path difference.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true. An initial \(\pi\) phase difference means destructive interference at the central point (where path difference is zero). Reason (R) is also true, as \(\Delta\phi = \frac{2\pi}{\lambda} \Delta x). (R) explains how phase difference relates to path difference, justifying (A).
Assertion (A): In YDSE central maxima means the maxima formed with zero optical path difference. It may be formed anywhere on the screen.
Reason (R): In an interference pattern, whatever energy disappears at the minimum, appears at the maximum.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Both Assertion (A) and Reason (R) are true statements. Central maxima is indeed defined by zero path difference, and its location can be shifted. Interference redistributes energy, meaning energy is conserved. However, (R) does not explain the definition or position of central maxima in (A).