Light and Sound

Question 1

What is a luminous object? Give an example.

Answer 1

A luminous object is something that gives off lights, for example the Sun; light is produced by luminous objects.

Question 2

What is a non-luminous object? Give an example.

Answer 2

A non-luminous object is something that does not emit light; for example a tennis ball.

Question 3

Why does light travel in straight lines?

Answer 3

Light travels in straight lines because light is a wave and waves travel in straight lines.

Question 4

What is a periscope?

Answer 4

A periscope is an instrument used for looking over or around objects which is stopped.

Question 5

What happens when white light is passed through a glass prism?

Answer 5

The light disperses into a spectrum of colours (ROYGBIV).

Red, Orange, Yellow, Green, Blue, Indigo, Violet

Question 6

How can we detect colours?

Answer 6

We can detect colours because of cone and rod cells which cover the retina (at the back of the eye).

Question 7

What is reflection?

Answer 7

Reflection is the throwing back by a body or surface of light, heat, or sound without absorbing it.

Question 8

What is refraction?

Answer 8

Refraction is the bending of light (it also happens with sound, water and other waves) as it passes from one transparent substance into another.

Question 9

How can colours be absorbed?

Answer 9

Coloured compounds absorb visible (coloured) light and this absorption is responsible for their colour.

Question 10

How can colours be reflected?

Answer 10

Objects appear colored because of the way they reflect light.

Question 11

How does sound travel using a medium using the particle theory?

Answer 11

When sound is created, the air particles vibrate and collide with each other, causing the vibrations to pass between air particles; therefore sound cannot travel through a vacuum.

Question 12

Which medium does sound travel the fastest through and why?

Answer 12

Sound travels fastest through solids. This is because molecules in a solid medium are much closer together than those in a liquid or gas, allowing sound waves to travel more quickly through it.

Question 13

Which is faster: sound or light?

Answer 13

Light waves travel much faster than sound waves. Light waves do not need a medium in which to travel but sound waves do.

Question 14

What is amplitude?

Answer 14

Amplitude is the relative strength of sound waves (transmitted vibrations), which we perceive as loudness or volume.

Question 15

What is frequency?

Answer 15

Frequency is the number of times per second that a sound pressure wave repeats itself.

Question 16

What is pitch?

Answer 16

The pitch of a sound is how high or low the sound is.

Question 17

How can we hear sounds?

Answer 17

1) Sound waves travel towards the ear canal by the pinna.
2) It then reaches the eardrum which vibrates.
3) These vibrations are carried to the cochlea, and the auditory nerve carries this information to the brain.

Question 18

How do loud noises damage hearing?

Answer 18

Listening to loud noises for a long time can overwork hair cells in the ear, which can cause these cells to die.

Question 19

What does the law of reflection state?

Answer 19

The Law of Reflection states that the angle of incidence is equal to the angle of reflection.