# Optics Quiz for Fun & Quiz Competition Practice 1

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## Results

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### #1. If a plane mirror is turned through 400, how much will the reflected ray turn through? (In degrees)

### #2. What will be the transverse magnification of a mirror if the lengths of object and image are, L0 = -6 cm, Li = 216 cm?

### #3. A concave mirror is held in water. What would be the change in the focal length of the mirror

### #4. The power of a plane mirror is ________.

### #5. If a ray is incident on a plane mirror at an angle of π/6, then it suffers a deviation of _______.

## Results

### #1. If a plane mirror is turned through 400, how much will the reflected ray turn through? (In degrees)

### #2. What will be the transverse magnification of a mirror if the lengths of object and image are, L0 = -6 cm, Li = 216 cm?

### #3. A concave mirror is held in water. What would be the change in the focal length of the mirror

### #4. The power of a plane mirror is ________.

### #5. If a ray is incident on a plane mirror at an angle of π/6, then it suffers a deviation of _______.

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Physics Quiz Explanation is given below

1.(c) If a plane mirror turns through a certain angle, the reflected ray turns through double the original angle. So here the plane mirror turns through 40^{0}, hence the reflected ray gets deviated, 2 x 40^{0 }= 80^{0}

2.(b) Transverse magnification is also called lateral magnification, which is equal to m.

Here m^{2 }= -L_{i}/L_{0}

So, m^{2} = – 216/ -6 = 36

Or, m = 6

3.(b) focal length won’t change because f doesn’t depend upon the external medium in which mirror is held.

4.(b) The power of a plane mirror is zero because,

For a plane mirror, f = ꚙ

Power, P = 1/f = 1/ ꚙ

= 0

5.(b) If a ray is incident on a plane mirror at a angle of incidence i , then it suffers a deviation of (π-2i).

Here i = π/6

So deviation, π-2i = π-(2x π/6) = 2π/3.

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1. If a plane mirror is turned through 40^{0}, how much will the reflected ray turn through? (In degrees)

a. 120

b. 50

c. 80 ()

d. 20

2. What will be the transverse magnification of a mirror if the lengths of object and image are, L_{0} = -6 cm, L_{i }= 216 cm?

a. -36 cm

b. +6 cm ()

c. – 60 cm

d. +36 cm

3. A concave mirror is held in water. What would be the change in the focal length of the mirror?

a. f will be halved

b. f won’t change ()

c. f will be doubled

d. f will change, as per the medium

4. The power of a plane mirror is ________.

a. Infinity

b. Zero ()

c. 1 D

d. None of the above

5. If a ray is incident on a plane mirror at an angle of π/6, then it suffers a deviation of _______.

a. π/6

b. 2π/3 ()

c. π/3

d. π/2