Light Reflection and Refraction Test

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Light Reflection and Refraction Test - 34

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Question 1
1 / -0

A ray of light travelling in air is incident on the plane of a transparent medium. The angle of incident is $$45^0$$ and that of refraction is $$30^0$$. The refractive index of the medium with respect to air is:

A
$$2$$

B
$$\dfrac {1}{\sqrt 2}$$

C
$$2\sqrt 2$$

D
$$\sqrt 2$$

Solution

Given:
Angle of incidence $$\angle i=45^0$$
Angle of refraction $$\angle r=30^0$$
Refractive index of transparent medium w.r.t. air is
$$\mu_{ma}=\dfrac{\mu_m}{\mu_a}=\dfrac{\mu_m}{1}=\mu_m$$
By Snell's Law,
$$\displaystyle \mu_m=\dfrac {sin \ i}{sin \ r}=\dfrac {sin \ 45^0}{sin \ 30^0}=\cfrac {\dfrac {1}{\sqrt 2}}{\dfrac {1}{2}}=\sqrt 2$$
Question 2
1 / -0

Find the refractive index of glass with respect to water. The refractive indices of glass and air with respect to air are $$3/2$$ and $$4/3$$ respectively.

A
$$2/1$$

B
$$1/2$$

C
$$9/8$$

D
$$8/9$$

Solution

Refractive index of medium $$1$$ with respect to medium $$2$$, $$^1\mu_2=\dfrac {\mu_2}{\mu_1}$$
Refractive index of glass with respect to air, $$^g\mu_a=\dfrac {3}{2}$$

Refractive index of water with respect to air,$$^w\mu_a=\dfrac {4}{3}$$
$$^g\mu_a=\dfrac {\mu^a}{\mu^g}$$

$$^w\mu_a=\dfrac {\mu^a}{\mu^g}$$

$$\therefore \text{refractive index of glass with respect to water,}\ \displaystyle ^g\mu_w=\dfrac {\mu_w}{\mu_a}\times \dfrac {\mu_a}{\mu_g}=\dfrac {^g\mu_a}{^w\mu_a}=\dfrac {3}{2}\times \dfrac {3}{4}=\dfrac {9}{8}$$
Question 3
1 / -0

In case of a virtual and erect image, the magnification of a mirror is :

A
Positive

B
Negative

C
Unity

D
Infinity

Solution

For any erect image, the magnification of a mirror is positive.
We know,
Magnification (M) $$ = \dfrac{\text{height of image}(h_i)}{\text{height of object}(h_o)}$$
The erect image formed same side of object to the principle axis.
So, In Sign convention, Sign of object height and image height will be same.
Hence Magnification will be positive.
Question 4
1 / -0

If the magnification of a body of size 1 m is 2, what is the size of the image?

A
1m

B
2m

C
3m

D
4m

Solution

$$m=2=\dfrac {h_i}{h_o}=\dfrac {h_i}{1}\Rightarrow h_1=2\times 1\ m$$
So, $$h_1=2\ m$$
Question 5
1 / -0

Formula of focal length in convex lens is

A
$$\displaystyle f = \frac{u+v}{u-v}$$

B
$$\displaystyle f = \frac{u\times v}{u-v}$$

C
$$\displaystyle f = \frac{u-v}{u+v}$$

D
$$\displaystyle f = \frac{u+v}{u+v}$$

Solution

$$\begin{array}{l}\text { Focal length of lens, from lens formula : } \\\qquad \begin{array}{l}\dfrac{1}{f}=\dfrac{1}{v}-\dfrac{1}{u} \\ \dfrac{1}{f}=\dfrac{u-v}{v \times u} \\ f=\dfrac{v \times u}{u-v}\end{array}\end{array}$$
Question 6
1 / -0

A light ray passing from crown glass to flint glass, then the speed of light is:

A
smaller in crown glass than in flint glass

B
larger in crown glass than in flint glass

C
same in crown glass and in flint glass

D
zero in crown glass and flint glass

Solution

Refractive index of flint glass(1.65) is more than that of crown glass(1.55). So, the speed of light in flint glass is lesser than that in crown glass.
Option B
Question 7
1 / -0

The rays parallel and close to the principal axis are called:

A
Converging rays

B
Diverging rays

C
Coherent rays

D
Paraxial rays

Solution

The rays parallel and close to the principal axis are called paraxial rays. The rays parallel but not close to the principal axis are called peripheral rays.
Question 8
1 / -0

The magnification produced by a concave mirror :

A
is always more than one

B
is always less than one

C
is always equal to one

D
may be less than, equal to or greater than one

Solution

Depending on the position of the object the magnification produced by a concave mirror may be less than, equal to or greater than one.
Question 9
1 / -0

Ratio of the size of the image to the size of the object is known as:

A
Focal plane

B
Transformation ratio

C
Efficiency

D
Magnification

Solution

Ratio of the size of the image to the size of the object is known as magnification. It is given by $$m = \dfrac{h_{i}}{h_{o}}$$
where $$m \rightarrow$$ magnification
$$h_{i} \rightarrow$$ height of image
$$h_{O} \rightarrow$$ height of object
Question 10
1 / -0

The distance between the extreme points on the periphery of the mirror is called:

A
focal length

B
radius of curvature

C
principal section

D
none of these

Solution

Principal section is also defined as the normal 'side view' of the mirror for a ray diagram. In the diagram AB is the principal section.

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Re-Attempt Weekly Quiz Competition

Light Reflection and Refraction Test - 34

Result

Light Reflection and Refraction Test - 34

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SHARING IS CARING

Question 1

$$2$$

$$\dfrac {1}{\sqrt 2}$$

$$2\sqrt 2$$

$$\sqrt 2$$

Solution

Question 2

$$2/1$$

$$1/2$$

$$9/8$$

$$8/9$$

Solution

Question 3

Positive

Negative

Unity

Infinity

Solution

Question 4

1m

2m

3m

4m

Solution

Question 5

$$\displaystyle f = \frac{u+v}{u-v}$$

$$\displaystyle f = \frac{u\times v}{u-v}$$

$$\displaystyle f = \frac{u-v}{u+v}$$

$$\displaystyle f = \frac{u+v}{u+v}$$

Solution

Question 6

smaller in crown glass than in flint glass

larger in crown glass than in flint glass

same in crown glass and in flint glass

zero in crown glass and flint glass

Solution

Question 7

Converging rays

Diverging rays

Coherent rays

Paraxial rays

Solution

Question 8

is always more than one

is always less than one

is always equal to one

may be less than, equal to or greater than one

Solution

Question 9

Focal plane

Transformation ratio

Efficiency

Magnification

Solution

Question 10

focal length

radius of curvature

principal section

none of these

Solution

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