Light Reflection and Refraction Test

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Light Reflection and Refraction Test - 20

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Question 1
1 / -0

The magnification of plane mirror is:

A
Infinite

B
2.0

C
1.0

D
0.0

Solution

The magnification of the plane mirror is 1 since the size of the image is the same as thesize of the object. The distance of the image from the mirror is the same asthe distance of the object from the mirror.
Magnification $(m) = \frac{H e i g h t o f t h e i m a g e}{H e i g h t o f t h e o b j e c t} = \frac{I m a g e d i s \tan c e}{O b j e c t d i s \tan c e}$
Hence, the correct option is (C).
Question 2
1 / -0

Which colour in the visible region has the greatest speed in a optically denser medium?

A
Red

B
Orange

C
Green

D
Violet

Solution

All components of light have the same speed (c) in a vacuum. In any other medium like glass, the red colour in the spectrum has the greatest speed.
$n_{r e d} < n_{v i o l e t}$
$∴ v_{r e d} > v_{v i o l e t}$
Hence, the correct option is (A).
Question 3
1 / -0

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

A
Frequency increases

B
Frequency decreases

C
Remains the same

D
None of these

Solution

The frequency of lightdepends on the source of light and remains the same during refraction. Thespeed of the light changes when a ray of light passes from one medium toanother. The speed of light is higher in a rarer medium than a densermedium. A ray of light traveling from a rarer medium to a denser mediumslows down, due to which there is a change in the wave-length.
Hence, the correct option is (C).
Question 4
1 / -0

When two prism, one up and one down in contact receive white light. What is the colour of light that will emerge out?

A
White colour

B
Red colour

C
Blue colour

D
Green colour

Solution

Upon passage through a triangular glass prism, the white light is separated into its component colors - red, orange, yellow, green, blue, indigo and violet. The separation of visible light into its different colors is known as dispersion.
The light that will emerge out of the combination of the two prisms, will be white in colour because the first prism will cause dispersion of light and the second prism will receive all the seven-coloured rays and recombines them into original white light.
Hence, the correct option is (A).
Question 5
1 / -0

In what direction does a ray of light bend, as it travels from a denser to a rarer medium?

A
doesn’t bend at all.

B
bends away from the normal.

C
bends towards the normal.

D
None of these

Solution

As a ray of light travels from a denser medium to a rarer medium, it bends away from the normal.
Hence, the correct option is (B).
Question 6
1 / -0

According to snell’s law, $n_{21} \times n_{12} =$ ?

A
$0.0$

B
$1.0$

C
$2.0$

D
$1212$

Solution

According to Snell'slaw of refraction, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a given pair of media, and for the lightof a given colour. If " $i$ " is the angle of incidence and " $r$ " is the angle of refraction, then:
$\frac{\sin i}{\sin r} =$ constant
$∴ n_{21} \times n_{12} = 1$
Hence, the correct option is (B).
Question 7
1 / -0

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

A
Concave mirror

B
Biconcave mirror

C
Convex mirror

D
Plane mirror

Solution

Convex Mirror is a curved mirror where the reflective surface bulges out towards the light source. This bulging out surface reflect light outwards and are not used to focus light.
A convex mirror is also known as a diverging mirror as this mirror diverges light when they strike on its reflecting surface. Virtual, erect, and diminished images are always formed with convex mirrors, irrespective of the distance between the object and the mirror.
Hence, the correct option is (C).
Question 8
1 / -0

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

A
$3 \times 10^{5} m . s^{- 1}$

B
$3 \times 10^{6} m . s^{- 1}$

C
$3 \times 10^{5} k m . s^{- 1}$

D
$3 \times 10^{8} k m . s^{- 1}$

Solution

The speed of light in free space (that is, in a vacuum) is a constant that has been measured to considerable accuracy. To nine significant figures, it is $299, 792, 458$ meters per second $(2.99792458 \times 10^{8} m / s) \approx 3 \times 10^{5} k m s^{- 1}$ .
Hence, the correct option is (C).
Question 9
1 / -0

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

A
Plane mirror

B
Convex

C
Concave

D
Reflecting mirror

Solution

A concave mirror has used an ophthalmoscope to examine the 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.
Hence, the correct option is (C).
Question 10
1 / -0

What colour will we get while mixing blue with green?

A
Black

B
Pink

C
Cyan

D
Yellow

Solution

By convention, the three primary colors in are red, green, and blue. When blue colour is mixed with green colour, cyan colour is obtained.
Hence, the correct option is (C).
Question 11
1 / -0

What is the relationship between focal length $(f)$ and radius of curvature $(R)$?

A
${f}=\frac{{R}}{2}$

B
${f}=\frac{{R}}{3}$

C
${f}=\frac{{R}}{4}$

D
${f}=\frac{{R}}{5}$

Solution

Focal length ( ${f}$ ) is the distance from the mirror at which the light rays coming parallel from infinity meet. The radius of Curvature ${R}$ is the radius of the sphere of which the mirror is a part. Focal length and radius of curvature are related as:
$\mathrm{f}=\frac{\mathrm{R}}{2}$
Hence, the correct option is (A).
Question 12
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 isplaced at the focus of the concave mirror, the image will be formed atinfinity. The image will be highly enlarged and will be real andinverted.
Hence, the correct option is (A).
Question 13
1 / -0

A convex lens is:

A
Thicker at the edges than at the middle.

B
Called a diverging lens.

C
Thicker at the middle than at the edges.

D
Of uniform thickness everywhere.

Solution

A convex lens always converges the light rays incident on it. Hence a convex lens is also called a converging lens. A convex lens(converging lens) is thicker in the middle than at the edges.
Hence, the correct option is (C).
Question 14
1 / -0

If the angle of incidence is $90 °$ , what is the angle of refraction?

A
$r = 1$

B
$r = 90 °$

C
$r = \sin^{- 1} (\frac{1}{n})$

D
$r = 45 °$

Solution

According to Snell'slaw of refraction, the ratio of the sine of the angle of incidence to the sin of the angle of refraction is a constant for a given pair of media, and for the lightof a given color. If " i " is the angle of incidence and " r" is the angle of refraction, then:
$\frac{\sin i}{\sin r} = n$
$\Rightarrow r = \sin^{- 1} (\frac{1}{n})$
Hence, the correct option is (C).
Question 15
1 / -0

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

A
3.5 D

B
2.5 D

C
6.6 D

D
4.5 D

Solution

The power of a lens isthe reciprocal of its focal length. It is a measure of the degree ofconvergence or divergence of light rays achieved by a particular lens. Thepower of a convex lens is positive.
Power of lens $= \frac{1}{f o c a l l e n g t h}$
Given, focal length $= 40 c m$ or $0.40 m$
Therefore, the power of the given convex lens.
$= \frac{1}{f o c a l l e n g t h} = \frac{1}{0.40} = 2.5 D$
Hence, the correct option is (B).

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Re-Attempt Weekly Quiz Competition

Light Reflection and Refraction Test - 20

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Light Reflection and Refraction Test - 20

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Question 1

Infinite

2.0

1.0

0.0

Solution

Question 2

Red

Orange

Green

Violet

Solution

Question 3

Frequency increases

Frequency decreases

Remains the same

None of these

Solution

Question 4

White colour

Red colour

Blue colour

Green colour

Solution

Question 5

doesn’t bend at all.

bends away from the normal.

bends towards the normal.

None of these

Solution

Question 6

0.0

1.0

2.0

1212

Solution

Question 7

Concave mirror

Biconcave mirror

Convex mirror

Plane mirror

Solution

Question 8

3×105 m.s−1

3×106 m.s−1

3×105 km.s−1

3×108 km.s−1

Solution

Question 9

Plane mirror

Convex

Concave

Reflecting mirror

Solution

Question 10

Black

Pink

Cyan

Yellow

Solution

Question 11

\({f}=\frac{{R}}{2}\)

\({f}=\frac{{R}}{3}\)

\({f}=\frac{{R}}{4}\)

\({f}=\frac{{R}}{5}\)

Solution

Question 12

Infinity

Beyond C

Between C and F

At C

Solution

$0.0$

$1.0$

$2.0$

$1212$

$3 \times 10^{5} m . s^{- 1}$

$3 \times 10^{6} m . s^{- 1}$

$3 \times 10^{5} k m . s^{- 1}$

$3 \times 10^{8} k m . s^{- 1}$

$r = 1$

$r = 90 °$

$r = \sin^{- 1} (\frac{1}{n})$

$r = 45 °$