JEE Physics Wave Optics MCQs Set B

Question. If frequency of light wave propagating in water is halved, its speed
(a) Remains same
(b) Becomes four times
(c) Is halved
(d) Is doubled

Answer: A

Question. Corpuscular theory of light predicts speed of light to be
(a) Greater in water than in vacuum
(b) Dependent on intensity of light
(c) Greater in vacuum than in water
(d) Independent of medium

Answer: A

Question. In Fraunhoffer diffraction from a single slit, wave front incident on the slit is
(a) Planar
(b) Spherical
(c) Cylindrical
(d) Either spherical or cylindrical

Answer: A

Question. Young’s double slit experiment is performed with monochromatic light. A thin film is introduced in front of one of the slits
(a) Intensity at position of first maxima may decrease
(b) Central maxima may remain unshifted
(c) Intensity at the position of central maxima may increase
(d) Intensity at the position of central maxima must decrease

Answer: A

Question. Apparent wavelength of light coming from a star moving away from earth is 0.02% more than its actual wavelength. Velocity of star is
(a) 60 km/s
(b) 30 km/s
(c) 90 km/s
(d) 120 km/s

Answer: A

Question. Diffraction is easily noticeable for sound waves than for light waves because sound waves
(a) Have longer wavelength
(b) Are high energy waves
(c) Are low intensity waves
(d) Are mechanical in nature

Answer: A

Question. Approximate thickness of oil film to observe interference of light (due to which it looks coloured) is
(a) 10^–3 mm
(b) 10 pm
(c) 1 cm
(d) 10 mm

Answer: A

Question. Slit widths in a Young’s double slit experiment are in the ratio 9 : 4. Ratio of intensity at minima to that at maxima is
(a) 1 : 25
(b) 1 : 16
(c) 16 : 81
(d) 4 : 9

Answer: A

Question. Width of slit in a single slit diffraction experiment such that 20 maxima of double slit interference pattern are obtained within central maxima of the diffraction pattern is (Slit separation for double slit arrangement = 2 mm)
(a) 0.2 mm
(b) 0.4 mm
(c) 0.1 mm
(d) 0.05 mm

Answer: A

Question. A star, which is emitting radiation at a wavelength of 5000 Å, is approaching the earth with a velocity of 1.5 × 10⁵ m/s. The change in wavelength of the radiation as received on the earth is
(a) 2.5 Å
(b) Zero
(c) 100 Å
(d) 25 Å

Answer: A

Question. In Young’s double-slit experiment, if the distance between the slits is halved and the distance between the slits and the screen is doubled, the fringe width becomes
(a) Four times
(b) Eight times
(c) Double
(d) Half

Answer: A

Question. In a Fresnel biprism experiment, the two positions of lens give separation between the slits as 16 cm and 9 cm respectively. What is the actual distance of separation?
(a) 12 cm
(b) 12.5 cm
(c) 14 cm
(d) 13 cm

Answer: A

Question.  Colours appear on a thin soap film and on soap bubbles due to the phenomenon of
(a) Interference
(b) Dispersion
(c) Refraction
(d) Diffraction

Answer: A

Question. In an interference experiment monochromatic light is replaced by white light, we will see
(a) A few coloured bands and then uniform illumination
(b) Equally spaced white and dark bands
(c) Uniform illumination on the screen
(d) Uniform darkness on the screen

Answer: A

Question. In Young’s double slit experiment carried out with light of wavelength 5000 Å, the distance between the slit is 0.2 mm and the screen is at 200 cm from the plane of slits. The central maximum is at x = 0. The third maximum will be at x equal to
(a) 1.5 cm
(b) 1.67 cm
(c) 0.5 cm
(d) 5.0 cm

Answer: A

Question. In Young’s experiment when sodium light of wave length 5893 Å is used, then 62 fringes are seen in the field of view. Instead, if violet light of wavelength 4350 Å is used, then the number of fringes that will be seen in the field of view will be
(a) 84
(b) 74
(c) 64
(d) 54

Answer: A

Question. Waves that cannot be polarised are
(a) Longitudinal waves
(b) Electromagnetic waves
(c) Transverse waves
(d) Light waves

Answer: A

Question. Two polaroids are kept crossed to each other. Now one of them is rotated through an angle of 45°. The percentage of incident light now transmitted through the system is
(a) 25%
(b) 50%
(c) 75%
(d) 15%

Answer: A

Question. Diameter of human eye lens is 2 mm. What will be the minimum distance between two points to resolve them, which are situated at a distance of 50 m from eye. The wavelength of light is 5000 Å?
(a) 1.525 cm
(b) 12.48 cm
(c) 4.28 mm
(d) 2.32 m

Answer: A

Question. In a double slit experiment, the two slits are 1 mm apart and the screen is placed 1 m away. A monochromatic light of wavelength 500 nm is used. What will be the width of each slit for obtaining ten maxima of double slit within the central maxima of single slit pattern?
(a) 0.2 mm
(b) 0.02 mm
(c) 0.1 mm
(d) 0.5 mm

Answer: A