Polytechnic Physics Set 4

61: At a temperature of 20°C, the minimum distance a person must be to hear an echo is

12.2 meters 17.2 meters 15.2 meters 34.4 meters

Answer: 34.4 meters

62: When converting low pitch sound to high pitch sound, we increase

Frequency Amplitude Velocity Wavelength

Answer: Frequency

63: The value of ‘g’ on the surface of the Moon is

Less than on the Earth’s surface More than on the Earth’s surface More than on the Earth None of these

Answer: Less than on the Earth’s surface

64: Which of the following relationships is correct?

g = GM/R² g = R²/GM GM/R R/GM

Answer: g = GM/R²

65: The value of ‘g’ is maximum

At the poles At the equator At both None of these

Answer: At the poles

66: Which of the following materials is not used in making lenses?

Water Glass Plastic Clay

Answer: Water

67: Which lens would you use to read a dictionary?

Convex lens with focal length of 50 cm Concave lens with focal length of 50 cm Convex lens with focal length of 5 cm Concave lens with focal length of 5 cm

Answer: Convex lens with focal length of 50 cm

68: The lens formula is

1/v & 1/u = 1/f 1/v + 1/u = 1/f v/u = 1/f None of these

Answer: 1/v + 1/u = 1/f

69: The minimum distance for clear vision for a normal person is

25 meters 2.5 cm 25 cm 2.5 meters

Answer: 25 cm

70: The image of an object is formed on the

Cornea Iris Pupil Retina

Answer: Retina

71: The mirror in a vehicle produces magnification

Less than one More than one Equal to one None of these

Answer: More than one

72: If your reflection appears upright in a mirror, the mirror is

Plane Concave Convex Plane or convex

Answer: Plane

73: Which part of the eye is donated after death?

Cornea Retina Pupil Iris

Answer: Cornea

74: The image formed on the retina is

Real and inverted Real and upright Virtual and inverted Virtual and upright

Answer: Real and inverted

75: Which of these is the mirror formula?

1/v + 1/u = 1/f 1/v – 1/u = 1/f v/u = 1/f None of these

Answer: 1/v – 1/u = 1/f

76: The formula for the power of a lens is

Diopter m.s⁻² m.s⁻¹ None of these

Answer: m.s⁻¹

77: According to Snell’s law

μ = sin i / sin r μ = sin r / sin i μ = sin i x sin r None of these

Answer: μ = sin i / sin r

78: The distance between the principal focus and the pole of a mirror is called

Focal length Focus Magnification None of these

Answer: Focal length

79: The power of a lens is

P = 1/f P = f P = v/u None

Answer: P = 1/f

80: When light travels from one medium to another, the change in its path is called

Reflection of light Refraction of light Both (A) and (B) None of these

Answer: Refraction of light