Optics

The refractive index of four substances A, B, C and D are 1.31,1.43,1.33, 2.4 respectively. The speed of light is maximum in:

• A

• B

• C

• D

Where should an object be placed so that a real and inverted image of same size is obtained by a

convex lens:

• f

• 2f

• Infinity

• Between f and 2f

A small bulb is placed at the principal focus of a convex lens, when the bulb switched on the lens will produce

• A convergent beam of light

• A divergent beam of light

• A parallel beam of light

• A coloured beam of light

Magnification of a convex lens is _____.

• Positive

• Negative

• Either positive or negative

• Zero

A convex lens forms a real, diminished point sized image at focus. Then the position of the object is at:

• Focus

• Infinity

• At 2f

• Between f and 2f

Power of lens is -4D then its focal length is:

• 4 m

• -40 m

• -0.25 m

• -2.5 m

In a myopic eye the image of the object is formed:

• Behind the retina

• On the retina

• In front of the retina

• On the blind spot

The eye defect presbyopia can be corrected by;

• Convex lens

• Concave lens

• Convex mirror

• Bi focal lens

Which of the following lens would you prefer to use while reading small letters found in a dictionary?

• A convex lens of focal length 5 cm

• A concave lens of focal length 5 cm

• A convex lens of focal length 10 cm

• A concave lens of focal length 10 cm

If VB, VG, VR be the velocity of blue, green and red light respectively in a glass prism, then which of the following statement gives the correct relation?

• VB = VG = VR

• VB > VG > VR

• VB < VG < VR

• VB < VG > VR