Umbra and Penumbra

Q.

Write a few differences between umbra and penumbra.

Q. Shadow cannot be formed when light passes through and fall on a screen .

1. cardboard
2. book
3. glass

Q.

A region of total darkness is called the penumbra.

1. True
2. False

Q. Why don't a burning matchstick shows a shadow on a screen.?

Q.

Umbra is that part of a shadow which is partially dark.

1. True
2. False

Q. In the diagram shown, what is the letter A and letter B pointing towards?

1. A-Umbra, B-Penumbra
2. A-Umbra, B-Antumbra
3. A-Penumbra, B-Antumbra
4. A-Penumbra, B-Umbra

Q.

Study the table given below and answer the questions that follow.

Material	Allows light to pass through it	Does it form a shadow?
Wood	No	Yes
Butter paper	Partially	Yes
Bricks	No	Yes
Glass	Yes	No
Cardboard	No	Yes
Metal	No	Yes
Frosted glass	Partially	Yes

Identify translucent objects from the table given above. Give reasons for your choice.

Q.

A translucent material forms a faint shadow.

Q. The shape and size of a shadow depends on
(a) the shape and size of the object.
(b) the position of the source of light.
(c) the distance between the source of light and object.
(d) all of the above

Q. What is an object, that reflects some light and transmits some light, called ?

1. Opaque
2. Translucent
3. Diffuse
4. Coloured

Q.

The shadow formed due to a point source of light has_____.

1. only umbra region

2. only penumbra region

3. both umbra and penumbra regions

4. either umbra or penumbra region depending on the distance of light source

Q.

Define the term penumbra?