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Question Bank No: 3

1. What is the magnification when an object is placed at 2f of a convex mirror

a)		1/3
b)		2/3
c)		1
d)		3/2

2. Light travels through a glass plate of thickness d. If n is the refractive index of glass and c is the velocity of light in vacuum, the time taken by light to travel through the glass plate is

a)		n/cd
b)		nc/d
c)		nd/c
d)		ndc

3. Luminous flux is expressed in

a)		Lumen
b)		Candela
c)		Weber
d)		Lue

4. For an equilateral prism the angle of minimum deviation is $30^{0} .$ Then the refractive index of the material of the prism is

a)		1/ $\sqrt{2}$
b)		$\sqrt{2}$
c)		2
d)		2 $\sqrt{2}$

5. A concave lens can be used as a simple magnifier if the object lies

a)		beyond f
b)		within the focal length
c)		between f and 2f
d)		at 2f

6. A spherical air bubble in water will act as

a)		convex lens
b)		concave lens
c)		glass plate
d)		plano convex lens

7. Two wave fronts are emitted from coherent sources of path difference between them is 2.1 micron. Face difference between the wave fronts at that point is 7.692 $π .$ Wave length of light emitted by source will be

a)		5386 $Å$
b)		5400 $Å$
c)		5460 $Å$
d)		5892 $Å$

8. Light propagates 2cm distance in glass of refractive index 1.5 in time $t_{0}$ . In the same time $t_{0}$ , light propagates a distance of 2.25 cm in a medium. The refractive index of the medium is

a)		4/3
b)		3/2
c)		8/3
d)		none of these

9. 2 non-coherent sources emit light beam of intensities I and 4I. The maximum and minimum intensities in the resulting beam are

a)		9I and 3I
b)		9I and 5I
c)		5I and I
d)		5I and 3I

10. The first diffraction minimum due to single slit diffraction is $θ$ , for a light of wave length 5000 $Å$ . If the width of the slit is $1 \times 10^{- 4}$ cm, then the value of $θ$ is

a)		$30^{0}$
b)		$45^{0}$
c)		$60^{0}$
d)		$15^{0}$

11. The refractive index of a prism depends on

a)		angle of the prism
b)		deviation produced by the prism
c)		intensity of light
d)		the wave length of light