Light and sound

Question 1

Define a luminous and non-luminous object and give examples.

4 marks

Answer 1

A luminous object is something that gives of light, for example a light bulb. A non-luminous object does not give off light, for example a tennis ball.

Question 2

Describe an experiment to show light travels in straight lines.

4 marks

Answer 2

Take several cards of paper and cut a small hole in each. Line up the holes in a straight line and shine a torch through. the light will reach the other side. However, if you move one of the cards so it is not a straight line, the light cannot pass through.

Question 3

What colours can white light be dispersed into?

7 marks

Answer 3

Red, orange, yellow, green, blue, indigo and violet.

Question 4

Describe an experiment to show that sound needs a medium.

4 marks

Answer 4

Put an electronic buzzer inside a sealed bell jar and turn it on. We will be able to hear the speaker. Now, drain the air from the jar. When the buzzer goes, we cannot hear it because there is no medium for the sound to pass through.

Question 5

Which medium does sound travel fastest through and why?

2 marks

Answer 5

Sound travels fastest through solids because the particles are closer together than the other states of matter.

Question 6

Which is faster: sound or light?

1 mark

Answer 6

Light is faster.

Question 7

Define amplitude, frequency and pitch and describe their waves.

5 marks

Answer 7

Amplitude is how loud a sound is and is how big the waves are. Frequency is how high or low a sound is and is how close together the waves are. Pitch is the same as frequency.

Question 8

Describe how we hear sound.

4 marks

Answer 8

Sound waves travel towards the ear and are funnelled into the ear canal by the pinna. It then reaches the eardrum which vibrates. These vibrations are carried by three tiny bones to the cochlea, and the auditory nerve carries this information to the brain.