Light Reflection and Refraction Test

Result

Light Reflection and Refraction Test - 30

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

What is known as linear magnification of spherical mirrors?

A
Ratio of size of image to size of object

B
Ratio of shape of image to size of object

C
Ratio of size of image to shape of object

D
None

Solution

Ratio of size of image to size of object is known as linear magnification of spherical mirrors.
Linear magnification (m) is the ratio of height of image to that of the object.
Question 2
1 / -0

A real image is

A
Always erect

B
Either erect or inverted

C
Always inverted

D
Neither erect nor inverted

Solution

$$\textbf{Part1: Definition}$$
Real image is found when the rays of light converge at a point after reflection on a mirror or after refraction through lens.
$$\textbf{Part2: Real image }$$
If we place an object above the x-axis then by geometry the rays will converge below the axis .
Therefore, the image formed will be an inverted image.
Hence , a real image is always inverted.
Question 3
1 / -0

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

A
$$1$$

B
$$2$$

C
Constant

D
Variable

Solution

The ratio of the sine of the incident angle $$(i)$$ to the sine of the refracted angle $$(r)$$ constant for a pair of two media and is equal to the refractive index of the media.
Question 4
1 / -0

A ray of light travels from a denser to a rarer medium then, the ray :

A
doesn't bend at all

B
bends towards the normal

C
bends away from the normal

D
goes along the normal

Solution

When light travels from denser to rarer medium, the velocity of light increases which results in bending of light away from the normal.
Question 5
1 / -0

The height of the image formed by an object of height $$10 cm$$ placed in front of a plane mirror is ________.

A
$$5 cm$$

B
$$10 cm$$

C
$$15 cm$$

D
$$20 cm$$

Solution

If an object is placed in front of a plane mirror, the size of the object remains same. This is the property of plane mirror. So the height of the object will be $$10 cm$$ only.
Question 6
1 / -0

When a ray of light travels from air to glass slab and strikes the surface of separation at $$90^o$$, then it ....... .

A
Bends towards normal

B
Bends away from normal

C
Passes unbent

D
Passes in zigzag way

Solution

When light ray travel normally from one medium to the other medium the light ray passes unbent without showing any refraction.
Question 7
1 / -0

A square wire of side $$3.0 cm$$ is placed $$25 cm$$ in front of a concave mirror of focal length $$10 cm$$, with its centre on the axis of the mirror and its plane normal to the axis. The area enclosed by the image of the wire is :

A
7.5 cm$$^{2}$$

B
6.0 cm$$^{2}$$

C
4.0 cm$$^{2}$$

D
3.0 cm$$^{2}$$

Solution

We know that the magnification of a concave mirror is given as $$m=\displaystyle\frac{f}{f-u}$$.
So, we get: $$m=\displaystyle\frac{-10}{-10-(-25)}=-\frac{2}{3}$$
Thus the length of the side gets magnified by this factor. The image length is thus $$\displaystyle\frac{2}{3}\times 3=2 cm$$
Area of the image is thus $$2\times 2=4 cm^2$$
Question 8
1 / -0

A needle of length $$5\ cm$$, placed $$45 cm$$ from a lens, forms an image on a screen placed $$90\ cm$$ on the other side of the lens. The type of lens and its focal length is:

A
Convex, $$30\ cm$$

B
Concave, $$30\ cm$$

C
Convex, $$60\ cm$$

D
Concave, $$60\ cm$$

Solution

Object distance, $$u = -45\ cm$$
image distance, $$v = 90\ cm$$
focal length, $$f$$
Using Lens formula,
$$\dfrac{1}{f} = \dfrac{1}{v} - \dfrac{1}{u}$$

$$\dfrac{1}{f} = \dfrac{1}{90} - \dfrac{1}{\left(-45\right)}$$

$$\dfrac{1}{f} = \dfrac{1 + 2}{90} = \dfrac{3}{90}$$

$$f = 30\ cm$$
Focal length is positive
$$\therefore$$ The type of lens is a convex lens
Question 9
1 / -0

If a spherical mirror is immersed in a liquid, its focal length will:

A
Increase

B
Decrease

C
Remain unchanged

D
Depend on the nature of liquid

Solution

Focal length is the property of the spherical mirror. So, it does not changes when immersed in liquid.
Question 10
1 / -0

A convex lens of focal length $$15\ cm$$ produces a virtual image at a distance of $$30\ cm$$ from the lens. The object distance is:

A
$$5\ cm$$

B
$$7.5\ cm$$

C
$$-10\ cm$$

D
$$10\ cm$$

Solution

Given, convex lens
Focal length, $$f=15\ cm$$
Object distance, $$v=-30\ cm$$ (virtual image, behind the lens)
Object distance,$$u$$

Using Lens formula,

$$\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}$$

$$\implies \dfrac{1}{u}=\dfrac{1}{v}-\dfrac{1}{f}$$

$$ \dfrac{1}{u}=\dfrac{1}{-30}-\dfrac{1}{15}$$

$$ \dfrac{1}{u}=\dfrac{-2-1}{30}$$

$$ \dfrac{1}{u}=\dfrac{-3}{30}$$

$$u=-10\ cm$$

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

Light Reflection and Refraction Test - 30

Result

Light Reflection and Refraction Test - 30

Score

-

Rank

-

SHARING IS CARING

Question 1

Ratio of size of image to size of object

Ratio of shape of image to size of object

Ratio of size of image to shape of object

None

Solution

Question 2

Always erect

Either erect or inverted

Always inverted

Neither erect nor inverted

Solution

Question 3

$$1$$

$$2$$

Constant

Variable

Solution

Question 4

doesn't bend at all

bends towards the normal

bends away from the normal

goes along the normal

Solution

Question 5

$$5 cm$$

$$10 cm$$

$$15 cm$$

$$20 cm$$

Solution

Question 6

Bends towards normal

Bends away from normal

Passes unbent

Passes in zigzag way

Solution

Question 7

7.5 cm$$^{2}$$

6.0 cm$$^{2}$$

4.0 cm$$^{2}$$

3.0 cm$$^{2}$$

Solution

Question 8

Convex, $$30\ cm$$

Concave, $$30\ cm$$

Convex, $$60\ cm$$

Concave, $$60\ cm$$

Solution

Question 9

Increase

Decrease

Remain unchanged

Depend on the nature of liquid

Solution

Question 10

$$5\ cm$$

$$7.5\ cm$$

$$-10\ cm$$

$$10\ cm$$

Solution

User

Question Analysis

My Perfomance

Score

-

Rank

-

Results Announcement on: coming Monday

Stay Tuned: We’ll update you on your result via email or SMS.