TEST SERIES - 64 (I)

A boy stands straight in front of a mirror at distance of 30 cm from it. He sees his erect image whose height is 1/5 of his real height. The mirror he is using is

• Plane

• Convex

• Concave

• None of the above

The focal length of the converging lens is measured for violet, green and red colours. It is respectively f v, f g and f r . We will find that

• f y = f r

• f v > f r

• f v < f r

• f g > f r

The function of the collimator in a spectrometer is

• To decrease the intensity of light

• To increase the intensity of light

• To obtain a parallel beam of light

• To obtain larger dispersion

The refractive index of a piece of transparent quartz is the greatest for

• Red light

• Yellow light

• Green light

• Violet light

When a ray of light enters a water filled glass tank from a glass face making a non-zero angle to the normal, the emergent ray from the opposite face will follow a path which is

• Same

• Deflected to the right

• Deflected to the left

• Parallel but not same

If the refractive angle of a prism is 60° and the minimum deviation is 30°, then the angle of incidence is

• 30°

• 60°

• 45°

• 90°

The image of an object formed by device is always virtual and small. The device may be

• Convex lens

• Concave mirror

• Concave lens

• None of the above

Two sources of wave are called coherent if

• Both have the same amplitude of vibration

• Both produce waves of the same wavelength

• Both produce waves of the same wavelength having a constant phase difference

• Both produce waves having the same velocity

Line spectrum is given by

• Sun

• Mercury vapour lamp

• Candle

• Electric bulb

When a ray of light is refracted by a prism such that the angle of deviation is minimum, then

• The angle of emergence is equal to the angle of incidence

• The angle of emergence is greater than the angle of incidence

• The angle of emergence is smaller than the angle of incidence

• The sum of the angle of incidence and the angle of emergence is equal to 90°