Class 8 Practice – Level 3 – Set 1 – Light

Total questions: 15

For a concave mirror, when an object is placed between the focus (F) and the mirror surface, where is the virtual image formed?

Beyond the center of curvature

At the center of curvature

Behind the mirror

At infinity

None

Light travels faster in air than in glass. If the speed of light in air is $ \displaystyle 3\times {{10}^{8}}$ m/s and in glass is $ \displaystyle 2\times {{10}^{8}}$ m/s, what is the approximate refractive index of glass with respect to air?

1.5

2.0

0.67

1.33

None

Which color of light is refracted the least when white light passes through a prism?

Violet

Red

Green

Blue

None

How does a periscope use mirrors to allow someone to see over an obstacle?

By forming real images at different angles

By magnifying the object

By reflecting light twice, at 45° angles

By splitting light rays into multiple paths

None

A concave mirror has a radius of curvature of 30 cm. What is its focal length?

60 cm

30 cm

15 cm

10 cm

None

A lens has a focal length of 0.25 m. What is the power of this lens in diopters?

0.25 D

4 D

2.5 D

10 D

None

Why can’t a virtual image be captured on a screen?

It does not form on a real plane

It’s always inverted

The rays physically converge at the screen

The image is only visible to the observer

None

An object is placed 20 cm in front of a convex lens with a focal length of 10 cm. Where will the image be formed?

10 cm from the lens on the opposite side

20 cm from the lens on the same side

20 cm from the lens on the opposite side

40 cm from the lens on the opposite side

None

If an object is placed at the focal point of a convex lens, the image will be formed:

At the other focal point

At infinity

On the object side of the lens

Between F and 2F

None

10.

Which condition is necessary for total internal reflection to occur?

Light travels from a denser to a rarer medium

Light travels from a rarer to a denser medium

The angle of incidence is less than the critical angle

The refractive index of the second medium is higher

None

11.

If the magnification produced by a concave mirror is -2, what does this indicate about the image?

The image is upright and twice the size of the object

The image is inverted and half the size of the object

The image is inverted and twice the size of the object

The image is upright and half the size of the object

None

12.

A rainbow is formed because:

Only refraction occurs in raindrops

Only dispersion occurs in raindrops

Both refraction and dispersion occur in raindrops

Reflection in air creates colors

None

13.

Which of the following statements about lateral inversion is correct?

It occurs in all mirrors

It only occurs in curved mirrors

It reverses top and bottom

It reverses left and right

None

14.

A lens has a power of -2.5 diopters. What type of lens is this?

Convex lens with short focal length

Concave lens with short focal length

Convex lens with long focal length

Concave lens with long focal length

None

15.

Under which conditions can a convex lens produce a virtual image?

When the object is at the center of curvature

When the object is between F and the lens

When the object is at infinity

When the object is beyond 2F

None

1 out of 15

Class 8 Practice – Level 3 – Set 1 – Light

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