Light Reflection and Refraction Test

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Light Reflection and Refraction Test - 55

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Question 1
1 / -0

A spherical mirror and a thin spherical lens have each a focal length of $$-15$$ cm. The mirror and lens are likely to be :

A
both concave

B
both Convex

C
the mirror is concave and lens is convex

D
the mirror is convex but lens is concave

Solution

Negative focal length is a characteristic of concave mirror and concave lens. Hence, both mirror and the lens are concave.
Question 2
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The center of the imaginary glass sphere of which the lens is a part is known as?

A
Centre of Curvature (C)

B
Optic Centre (O)

C
Principal Focus of Convex Lens (F)

D
Aperture

Solution

The center of the imaginary glass sphere of which the lens is a part is known as the center of curvature (C). It is found at a point that is at a distance from the curve equal to the radius of curvature lying on the normal vector. It is the point at infinity when the curvature is zero.
Question 3
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A point within the lens, where a line drawn through the diameter of lens meets principal axis is known as

A
Focal length

B
Optic Center

C
Aperture

D
Center of curvature

Solution

Correct answer is (b).

Optic centre is a point within the lens, where a line drawn through the diameter of lens meets principal axis and through which light passes without undergoing any deviation so a ray of light passing through the optical center does not changes its direction.
Question 4
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The speed of light in glass slab is ________ compared to that in air. Fill in the gap.

A
more

B
less

C
the same

D
can not be decided

Solution

The refractive index of a medium is defined as $$n=\dfrac{c}{v}$$, where $$c$$ is the speed of light in the air and $$v$$ is the speed of light in the medium.
The refractive index of the glass slab is $$n=1.5$$, which is greater than $$1$$. Therefore, $$c>v$$ or $$v<c$$.
Thus the speed of light in the glass slab is less as compared to the speed of light in the air.
Question 5
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Which of the below term has the property where light rays passing through this point emerge without deviation from lens?

A
Optical Center

B
Center of curvature

C
Radius of curvature

D
Focal length

Solution

Correct answer is (a)

Optical Center has the property where light rays passing through this point emerge without deviation from lens. Also it is a point within the lens, where a line drawn through the diameter of lens meets the principal axis.
Question 6
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Which of the below is one of the laws of refraction?

A
The incident ray, the normal and the refracted ray, all lie in a different plane.

B
The incident ray, the normal and the refracted ray, all lie in the same plane.

C
The incident ray, the normal and the refracted ray, all lie in opposite plane.

D
The incident ray and the refracted ray, both lie in a plane.

Solution

$$\text{The incident ray, the normal and the refracted ray, all lie in the same plane}$$ - is one of the laws of refraction.
Question 7
1 / -0

A parallel beam of light rays travelling parallel to principal axis after passing through the lens actually meet. This phenomena happens for which type of lens?

A
Concave

B
Convex

C
Bipolar

D
Cylindrical

Solution

Convex lense is a converging lens in which Parallel light rays beam travel parallel to principal axis after passing through the lens and converge at one point called the principal focus.
Correct answer is (b).
Question 8
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What is principal focus for concave lens?

A
It is a point on the principal axis of a concave lens from which a parallel beam of light rays, travelling parallel to the principal axis, appears to come after passing through the lens.

B
It is a point on the principal axis of a concave lens from which a perpendicular beam of light rays, travelling perpendicular to the principal axis, appears to come after passing through the lens.

C
It is a point on the principal axis of a convex lens at which a parallel beam of light rays, travelling parallel to principal axis, meet after passing through the lens.

D
None

Solution

Correct answer is (a)
Principal focus is a point on the principal axis of a concave lens from which a parallel beam of light rays, travelling parallel to the principal axis appears to come after passing through the concave lens.
Question 9
1 / -0

How many center of curvatures does a biconvex lens possess?

A
4

B
3

C
2

D
1

Solution

Correct answer is (c)

Biconvex lenses are simple lens comprising two convex spherical surfaces, generally with the same radius of curvature and hence it has 2 centre of curvatures.
Question 10
1 / -0

What is refraction?

A
Phenomenon in which ray of light deviates from its path at the surface of separation of two media.

B
Phenomenon in which ray of light reflects from its path at the surface of separation of two media.

C
Phenomenon in which ray of light deviates from its path at the surface of 1st media

D
None

Solution