Light Energy Questions

Light is a form of energy which can be seen in the form of visible light. Light features packets of energy known as photons. Light travels in the form of a wave when it travels. The light speed is equal to 186,282 miles per second. The electromagnetic spectrum features an entire range of all possible frequencies of radiation.

When white light passes through a prism, it disperses. Change in the direction of a wave passing from one medium to another is known as refraction. Bouncing back of light rays when it approaches a smooth polished surface is called reflection.

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Important Light Energy Questions with Answers

1. Which of the following is optically denser?

1. Air
2. Water

Answer: b) Water

Explanation: The speed of light in air is higher than the speed of light in water. Water is optically denser than air.

2. The splitting of white light into its constituent colours is known as _______

1. Reflection
2. Refraction
3. Dispersion
4. Interference

Answer: c) Dispersion

Explanation: Dispersion is a phenomenon in which the beam of light splits into constituent colours.

3. Humans are able to see _______

1. Gamma rays
2. X-rays
3. Visible light
4. Ultraviolet rays

Answer: c) Visible light

Explanation: Visible light can be easily seen through human eyes.

4. When a ray of light travels from water to air, it bends ______

1. Towards the normal
2. Away from the normal

Answer: b) Away from the normal

Explanation: Lightray bends away from the normal when light ray travels from water to air.

5. List five uses of light.

• It is used to power satellites and space stations.
• It helps to view objects clearly.
• Light is used in many electronic appliances.
• It helps plants to make food and grow.
• It is used in cooking and other domestic purposes.

6. The angle between the normal and refracted ray is known as _______

1. Angle of incidence
2. Angle of deviation
3. Angle of emergence
4. Angle of refraction

Answer: d) Angle of refraction

Explanation: The angle of refraction is the angle between the normal and refracted ray.

7. What is the wavelength of visible light?

The wavelengths of visible light range between 400-700 nanometers.

8. When white light passes through a prism it ______

1. Converges
2. Diverges
3. Disperses
4. Neither converges nor diverges

Answer: c) Disperses

Explanation: When white light passes through a prism, it disperses.

9. Name three natural sources of light.

Natural sources of light are light from the Sun, lightning, and glowworms.

10. Lowest frequency of an electromagnetic spectrum is occupied by _____.

1. X-rays
2. Ultraviolet rays
3. Radio waves
4. Gamma rays

Answer: c) Radio waves

Explanation: Radio waves occupy the lowest frequency of the electromagnetic spectrum.

Does light behave like a wave?

Practice Questions

1. What is light?
2. What is meant by electromagnetic spectrum?
3. Explain the electromagnetic spectrum.
4. What are photons?
5. Can light travel as a wave?