Light Reflection and Refraction Test

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Light Reflection and Refraction Test - 54

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Weekly Quiz Competition

Question 1
1 / -0

During refraction of light, which of the following quantity does not change?

A
Velocity

B
$$\displaystyle \lambda $$

C
Amplitude

D
Frequency

Solution

Frequency of light does not change on refraction , When a ray of light passes from one medium to another, its direction (or path) changes because of change in speed of light from one medium to another.
Question 2
1 / -0

For the same angle of incidence, the angles of refraction in media P, Q, R and S are $$50^o, 40^o, 30^o, 20^o$$, respectively. The speed of light is minimum in medium :

A
P

B
Q

C
R

D
S

Solution

Velocity of light in air is $$c$$
$$\therefore$$ Velocity of light in a medium, $$v = \dfrac{c}{n}$$ ..........(1)
where, $$n$$ is the refractive index of the medium
Also from Snell's law of refraction: $$1 \times sini = n \times sin r$$
$$\implies$$ $$n = \dfrac{sin i}{sin r}$$
Thus equation (1) becomes: $$v = \dfrac{c \times sin r }{sin i}$$
$$\implies$$$$v \propto sin r$$$$(\because i = constant)$$
As for medium $$S$$, $$r = 20^o$$ which is minimum
$$\implies v$$ is minimum in medium $$S$$
Question 3
1 / -0

Refraction of light can take place at boundary of

A
Transparent Media

B
Opaque Media

C
Any Medium

D
Rarer Medium

Solution

Correct answer (c)
Refraction of light can take place at boundary of any medium. The refraction of light when it passes from a fast medium to a slow medium bends the light ray toward the normal to the boundary between the two media. Snell's law can be derived from Fermat's Principle or from the Fresnel Equations
Question 4
1 / -0

Mirror made by silvering the outer surface of the piece of a hollow sphere:

A
convex mirror

B
concave mirror

C
both

D
none

Solution

Mirror made by silvering the outer surface of the piece of a hollow sphere is concave in nature. Because reflection will take place from inner side of spherical part.
Question 5
1 / -0

Mirror made by silvering the inner surface of the piece of a hollow sphere is:

A
convex mirror

B
concave mirror

C
both

D
none

Solution

A convex mirror made by silvering the inner surface of the piece of a hollow sphere is such that the reflection takes place from the outer (bulging) surface.
Question 6
1 / -0

A light is travelling from air into a medium. The velocity of light in a medium is reduced to 0.75 times the velocity in air. Assume that angle of incidence $$i$$ is very small, the deviation of the ray is :

A
$$i$$

B
$$\dfrac{i}{3}$$

C
$$\dfrac{i}{4}$$

D
$$\dfrac{3i}{4}$$

Solution

Let velocity of light in air be $$v$$.

Velocity of light in medium, $$v_m = \dfrac{v}{n}$$ where $$n$$ is the refractive index of the medium.

$$\therefore$$ $$0.75 v =\dfrac{v}{n}$$ $$\implies n = \dfrac{4}{3}$$

Given : $$n_1 =1$$

Using Snell's law of refraction: $$1\times sin i = n \times sin r$$...............(1)

But it is given that angle of incidence is very small, i.e $$sin i \approx i$$

Hence angle of refraction is also very small $$\implies sin r \approx r$$

$$\therefore$$ From equation (1), $$ i = \dfrac{4}{3} r$$

Now angle of deviation, $$\delta = i -r = i - \dfrac{3}{4}i$$ $$\implies \delta = \dfrac{i}{4}$$
Question 7
1 / -0

According to laws of refraction(Snell's law) :

A
$$\angle i=\angle r$$

B
$$sin \ i = sin \ r$$

C
$$\dfrac{sin \ i}{sin \ r}$$ = constant

D
$$tan \ i = tan \ r$$

Solution

According to the second law of refraction, also known as Snell's law, the ratio of sine of the angle of incidence to the sine of angle of refraction is a constant for a given pair of media.

$$ \Rightarrow \dfrac{\sin\ i}{\sin\ r} = Constant $$

This constant is known as the refractive index of the medium.

Hence, the correct answer is OPTION C.
Question 8
1 / -0

Equi convex is a type of ______ lens. Fill in the blank.

A
Diverging

B
Converging

C
Both

D
None

Solution

A convex lens may be of the following types
1. Biconvex or double convex or equiconvex
2. Plano-convex
3. Convexo convex
A convex lens is always converging
Question 9
1 / -0

A convex mirror used for rear view on an automobile has a radius of curvature of 3.00m. If a bus is located at 5.00m from this mirror, find magnification?

A
+0.23

B
-0.23

C
+0.45

D
-0.45

Solution

$$\dfrac{2}{R}=\dfrac{1}{u}+\dfrac{1}{v}$$
$$\dfrac{2}{3}=\dfrac{1}{-5}+\dfrac{1}{v}$$
$$\dfrac{1}{v}=0.866 \Rightarrow v = 1.15$$ cm
Magnification
$$=-\dfrac{v}{u}=-\dfrac{1.15}{-5}=0.23$$
Question 10
1 / -0

Which one of the following materials cannot be used to make a lens?

A
Water

B
Glass

C
Plastic

D
Clay

Solution

Hint: The principle of the lens is to refract the light ray for forming the image of the objects.

Step 1: Analysing the property of the lens,
$$\bullet$$As the light rays transmitted from the lenses, therefore the lens must be transparent.
$$\bullet$$Water, glass, and plastic are available in the transparent form while the clay is not the transparent material.
Therefore option (D) is the right answer.

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Light Reflection and Refraction Test - 54

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Light Reflection and Refraction Test - 54

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Question 1

Velocity

$$\displaystyle \lambda $$

Amplitude

Frequency

Solution

Question 2

P

Q

R

S

Solution

Question 3

Transparent Media

Opaque Media

Any Medium

Rarer Medium

Solution

Question 4

convex mirror

concave mirror

both

none

Solution

Question 5

convex mirror

concave mirror

both

none

Solution

Question 6

$$i$$

$$\dfrac{i}{3}$$

$$\dfrac{i}{4}$$

$$\dfrac{3i}{4}$$

Solution

Question 7

$$\angle i=\angle r$$

$$sin \ i = sin \ r$$

$$\dfrac{sin \ i}{sin \ r}$$ = constant

$$tan \ i = tan \ r$$

Solution

Question 8

Diverging

Converging

Both

None

Solution

Question 9

+0.23

-0.23

+0.45

-0.45

Solution

Question 10

Water

Glass

Plastic

Clay

Solution

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