Light energy

After the lights have been switched off, what can you see and what caused the difference?

• You see darkness because there is no light source.

• You see everything clearly because your eyes adjust instantly.

• You see only red objects because they glow in the dark.

• You see bright spots because the room gets illuminated.

What is light energy and what are its uses?

• Light energy is a form of energy that helps us to see the things around us. The Sun is the main source of light energy on the Earth. Light energy can also be used to guide traffic, to communicate, and in cameras.

• Light energy is a type of sound that helps us to hear better. The Sun is not related to light energy. Light energy is mainly used for cooking.

• Light energy is a form of heat that only comes from fire. It is used to keep us warm and cook food.

• Light energy is a type of mechanical energy that helps machines to work. It is not related to the Sun and is not used for communication.

List one use of light energy other than helping us to see the things around us.

• To guide traffic, to communicate, or in cameras.

• To cool down objects quickly.

• To make objects heavier.

• To produce sound.

The lights of a traffic light let us know when it is safe to cross the road.

• True

• False

Lighted messages on buildings can be read during both ___ and night.

• day

• rain

• fog

• storm

A camera requires ___ to take photographs.

• light

• water

• sand

• oil

Lasers produce beams of light that are strong enough to cut through ___.

• metals

• paper

• plastic

• wood

A laser can cut cleanly through ___.

• metals

• paper

• plastic

• wood

Quick Check: The uses of light energy and heat energy in your school include which of the following?

• Lighting classrooms and keeping rooms warm

• Cooling rooms and making ice

• Producing sound and storing data

• Generating electricity and running computers

Heat energy is defined as the energy transferred from one body to another due to a difference in temperature. What are its uses?

• It is used for cooking, heating, and generating electricity.

• It is used for storing data in computers.

• It is used for making objects invisible.

• It is used for transmitting radio signals.