Light, shadow & reflection

A glowing LED bulb and a ringing bell are kept in a vaccum jar. A person looking at the jar will

• see the bulb glowing and hear the bell ringing

• hear the bell ringing but will not see the bulb glowing

• see the bulb glowing but will not hear the bell ringing

• neither see the glowing bulb nor hear the ringing bell

What would be the colour of the shadow of a green ball?

• Black

• green

• Blue

• None of these

You will see the shortest shadow of yourself in sunlight .......

• in the morning

• in the evening

• at noon

• in the night

Which of the following is not always necessary to observe a shadow?

• sun

• source of light

• screen

• opaque object

Ahmed observed the shadow of a tree at 8:00 am, 12:00 noon and 3:00 pm. Which of the following statements is closest to his observation about the shape and size of the shadow?

• the shape of the shadow of the tree changes but the size remains the same

• the size of the shadow of the tree changes but the shape remains the same

• Both the size and shape of the shadow of the tree change

• Neither the shape nor the size of the shadow changes

Opaque material

• objects that emit light of their own

• a material that allows most of the light to pass through it

• a material that allows only a part of light to pass through it

• a material that does not allow any light to pass through it

A patch of light is observed at B, when the torch is lighted as shown. Which of the following is kept at position A to get this patch of light?

• A wooden board

• A glass sheet

• A mirror

• A sheet of white papers.

Look at the figure. What difference can be seen in the shadow formed on the screen in A and B ?

• shadow of A will be round

• shadow of B will be round

• Shadow of A will be bigger than shadow of B

• both will form the same type of shadow

Lunar eclipse

• shadow cast by the moon on the earth

• shadow cast by the moon on the sun

• shadow cast by the earth on the moon

• shadow cast by the earth on the sun

Solar eclipse

• shadow cast by the moon on the earth

• shadow cast by the moon on the sun

• shadow cast by the earth on the moon

• shadow cast by the earth on the sun