981. In a double-slit experiment if one of the two slits is covered then:
A. No interference fringes are observed
B. No diffraction fringes are observed
C. No fringes observed
D. Interference pattern not disturbed
982. Gives the definition of a meter in terms of the wavelength of red cadmium light:
A. Newton
B. Einstein
C. Michelson
D. Galileo
983. In Michelson interferometer to switch the fringe from bright to dark the mirror should be displaced through:
A. λ / 2
B. λ/3
C. λ/6
D. λ/4
984. In the shadow of a ball, the central portion appears bright that happens due to:
A. Interference
B. Diffraction
C. Polarization
D. Refraction
985. Which experiment shows that the wavelength of light is smaller than that of sound?
A. Diffraction
B. Polarization
C. Interference
D. Reflection
986. Crystals of a material can behave as:
A. Convex lens
B. Interferometer
C. Diffraction grating
D. Concave
987. If the mass of the body is 5 kg raised of 1 m. Then the work done is?
A. 0.49 J
B. 4.9 J
C. 49 J
D. 490 J
988. If a 50kg gate is pushed through 2m across the floor with a force of 50 N. The work done will be?
A. 100 J
B. 150 J
C. 200 J
D. 245 J
989. If the direction of force is perpendicular to the direction of motion of the body, then work done is?
A. Zero
B. Infinity
C. Minimum
D. Maximum
990. When the force is parallel to the direction of the body, the work done is?
A. Varies
B. Infinity
C. Minimum
D. Maximum
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