Light Reflection and Refraction Test

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Light Reflection and Refraction Test - 14

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Weekly Quiz Competition

Question 1
1 / -0

Virtual, erect and diminished image are the characteristic features of a:

A
Convex mirror

B
Plane mirror

C
Biconcave mirror

D
Concave mirror

Solution

A convex mirror always forms an erect, and a virtual and diminished image, for any position of the object.
Question 2
1 / -0

How does the frequency of a beam of ultra-violet light change when it goes from air into glass?

A
Frequency decreases

B
None of these

C
Frequency increases

D
Remains the same

Solution

The frequency of light depends on the source of light and remains the same during refraction. The speed of the light changes when a ray of light passes from one medium to another. The speed of light is higher in a rarer medium than a denser medium. A ray of light travelling from a rarer medium to a denser medium slows down, due to which there is a change in the wave-length.
Question 3
1 / -0

Where will the image be formed if the object is at the focus of the concave mirror?

A
Infinity

B
Beyond C

C
Between C and F

D
At C

Solution

If the object is placed at the focus of the concave mirror, the image will be formed at infinity. The image will be highly enlarged, and will be real and inverted.
Question 4
1 / -0

A convex lens has a focal length of 40 cm. Calculate its power.

A
6.6 D

B
4.5 D

C
3.5 D

D
2.5 D

Solution

The power of a lens is the reciprocal of its focal length. It is a measure of the degree of convergence or divergence of light rays achieved by a particular lens. The power of a convex lens is positive.

Power=1focallengthPower=1/ focallength

Given, focal length = 40 cm or 0.40 m

Therefore, Power of the given convex lens=1/ focallength = 1/0.40=2.5D
Question 5
1 / -0

According to snell’s law, n₂₁×n₁₂ = ?

A
1/2

B
1.0

C
2.0

D
0.0

Solution

According to Snell's law of refraction, the ratio of the sine of angle of incidence to the sine of angle of refraction is a constant for a given pair of media, and for the light of a given colour. If " i " is the angle of incidence and " r " is the angle of refraction, then:

sin i/sin r = constant

∴n₂₁×n = 1
Question 6
1 / -0

A convex lens is:

A
Of uniform thickness everywhere.

B
Called a diverging lens.

C
Thicker at the middle than at the edges.

D
Thicker at the edges than at the middle.

Solution

A convex lens (converging lens) is thicker at the middle than at the edges. A concave lens (diverging lens) is thicker at the edges than at the middle.
Question 7
1 / -0

Which type of mirror is used in ophthalmoscope to examine throat and ear?

A
Concave

B
Convex

C
Plane mirror

D
Reflecting mirror

Solution

A concave mirror is used in ophthalmoscope to examine throat and ear. A concave mirror forms an enlarged image of the part being examined by a physician. An image formed by a plane mirror is of an equal size as that of the object, whereas a convex mirror always forms a diminished image, for any position of the object.
Question 8
1 / -0

If the angle of incidence is 90^∘, what is the angle of refraction?

A
r = 90^∘

B
r = 1

C
r = sin-1 (1/n)

D
r = 45^∘

Solution

According to Snell's law of refraction, the ratio of the sine of angle of incidence to the sine of angle of refraction is a constant for a given pair of media, and for the light of a given colour. If " i " is the angle of incidence and " r " is the angle of refraction, then:

sin i /sin r = n ⟹ r = sin-1 (1/n)
Question 9
1 / -0

What is the value of speed of light in free space?

A
3×10⁸km.s−1

B
3×10⁵m.s−1

C
3×10⁵km.s−1

D
3×10⁶m.s−1

Solution

The value of speed of light in free space is 3×10⁵km.s⁻¹ or 3×10⁸m.s⁻¹

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Light Reflection and Refraction Test - 14

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Light Reflection and Refraction Test - 14

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Question 1

Convex mirror

Plane mirror

Biconcave mirror

Concave mirror

Solution

Question 2

Frequency decreases

None of these

Frequency increases

Remains the same

Solution

Question 3

Infinity

Beyond C

Between C and F

At C

Solution

Question 4

6.6 D

4.5 D

3.5 D

2.5 D

Solution

Question 5

1/2

1.0

2.0

0.0

Solution

Question 6

Of uniform thickness everywhere.

Called a diverging lens.

Thicker at the middle than at the edges.

Thicker at the edges than at the middle.

Solution

Question 7

Concave

Convex

Plane mirror

Reflecting mirror

Solution

Question 8

r = 90∘

r = 1

r = sin-1 (1/n)

r = 45∘

Solution

Question 9

3×108km.s−1

3×105m.s−1

3×105km.s−1

3×106m.s−1

Solution

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r = 90^∘

r = 45^∘

3×10⁸km.s−1

3×10⁵m.s−1

3×10⁵km.s−1

3×10⁶m.s−1