# Free Light, Shadows and Reflection 01 Practice Test - 6th grade

Which of the following object is luminous?

A.

Mirror

B.

Moon

C.

Earth

D.

Sun

#### SOLUTION

Solution : D

Luminous objects emit their own light. This light may come to our eyes directly or through reflection by non-luminous objects enabling us to see. Examples of luminous objects are stars, flashlight etc.

Chintu was holding an object in his hand and he was able to see Mintu through the object very clearly. What could the object possibly be?

A. Cardboard sheet
B. Metal sheet
C. Glass sheet
D. Notebook

#### SOLUTION

Solution : C

A material which allows light to completely pass through it is called as transparent material. One can easily see objects on the other side of a transparent object. Out of the given options, glass is the only transparent material. So, Chintu would be holding a glass sheet.

Which of the following objects is not transparent?

A. Smoke
B. Air
C. Pure water
D. Clear glass

#### SOLUTION

Solution : A

Among the given options, smoke is not transparent because, we cannot clearly see things through it. It does not allow all the light to completely pass through it as it is translucent in nature.

Opaque objects allow light to pass through them partially.

A. True
B.

False

#### SOLUTION

Solution : B

Opaque objects are those that do not allow light to pass through them. For example: wood, plastics etc.
On the other hand translucent materials are those that allow only some light to pass through them. Examples of translucent materials are tracing paper, frosted glass and thin cloth.

Which of the following statements is true?

A. Shadow is formed when a transparent object comes in the path of light.
B. Shadow is formed when an opaque object comes in the path of sound.
C. Shadow is formed when an opaque object comes in the path of light.
D. Shadow is formed when a transparent object comes in the path of sound.

#### SOLUTION

Solution : C

A shadow is formed when light is blocked by an opaque or translucent object. Opaque objects, such as a tree, completely block light and form a dark shadow. Transparent objects, such as glass, do not create a shadow because the light completely passes through them.

The reason behind the formation of a shadow and an image is the same.

A.

True

B.

False

#### SOLUTION

Solution : B

Shadow formation is due to obstruction of light by an opaque or translucent object which causes darkness on the screen behind. Image formation is due to reflection of light rays from an object. These two are completely different phenomena. Hence, it is false.

Which of the following is an opaque object?

A. Glass
B. Mirror
C. Air
D. Pure water

#### SOLUTION

Solution : B

Opaque objects do not allow light to pass through.
A mirror is an opaque object since it reflects light and the light cannot pass through the mirror.

Glass, air and water are transparent as they let light pass through them completely.

Which of the following is not a necessary requirement to see an object?

A. Light
B. Object
C. Eyes
D. Mirror

#### SOLUTION

Solution : D

Among the given options, light is necessary as it is responsible for the sensation of vision or in other words it enables us to see. Without eyes, we can not sense light. The object is obviously necessary as we can not see something which does not exist. A mirror is required only when we want to see the reflection of an object.

Which of the following is necessary for the formation of a shadow?

A. Glass
B. Mirror
C. Light
D. Air

#### SOLUTION

Solution : C

Shadow is formed on a surface only when the light is obstructed by an opaque or a translucent object. So, for the shadow formation, there should be a surface, an opaque or transluent object and incident light on the object.

Which of the following surfaces produce clear images?

A. Translucent surface
B. Unpolished and non-reflecting surface
C. Polished and plane reflecting surface
D. Transparent surface

#### SOLUTION

Solution : C

Polished and plane reflecting surfaces without irregularities and unevenness produce clear images as they cause regular reflection.
Transparent objects causes no reflection.
Only partial reflection occurs in translucent surfaces and hence, image, if formed is unclear.