Chapter 6

Question 1

What are the features of light?

Answer 1

1. Light is a form of radiation.
2. Light travels in straight lines.
3. Light transfers energy.
4. Light travels as a wave.
5. Light can travel through empty space.
6. Light is the fastest thing there is. (speed of light, universal speed limit)

Question 2

What are photons?

Answer 2

Tiny energy particles that make up light.

Question 3

What is the difference between longitudinal and transverse waves?

Answer 3

Longitudinal waves: oscillations that are parallel to the direction of energy transfer.
Transverse waves: oscillations that are 90 degrees to the direction of energy transfer.

Question 4

What is the amplitude of a wave?

Answer 4

Maximum distance from the peak to the equilibrium line.

Question 5

What are the two sections of a longitudinal wave?

Answer 5

Compressions and rarefractions.

Question 6

What is the unit of speed?

Answer 6

Meters per second (m/s)

Question 7

What is frequency?

Answer 7

The number of oscillations passing any point per second.

Question 8

What is the unit of frequency?

Answer 8

Hz.

Question 9

What is a period?

Answer 9

The time for one oscillation to pass any point.

Question 10

What is wavelength?

Answer 10

The distance between any point on a wave and it’s equivalent on the next oscillation.

Question 11

What is the wave equation?

Answer 11

Speed = Frequency x Wavelength

Question 12

What is regular reflection?

Answer 12

When waves bounce off a flat surface at the same angle they strike it.

Question 13

What is refraction?

Answer 13

The change in the direction of a wave passing from one medium to another caused by it’s change in speed.

Question 14

What is Diffraction?

Answer 14

Is when waves bend around the sides of an obstacle or spread out as they pass through a gap.

Question 15

When is Diffraction significant?

Answer 15

Diffraction is only significant if the size of the gap is about the same size as the wavelength.

Question 16

What are the features of sound waves?

Answer 16

1. Sound waves are caused by vibrations.
2. Sound waves are longitudinal waves.
3. Sound waves need material to travel through (medium)
4. Sound waves can travel through solids, liquids and gases.

Question 17

How are sound waves displayed graphically?

Answer 17

Using a microphone and a oscilloscope sound waves enter the microphone and vibrate a crystal or metal plate. These vibrations are changed into electrical oscillations on the oscilloscope.

Question 18

If sound waves are longitudinal, why are transverse waves seen on a oscilloscope when someone whistles into a microphone?

Answer 18

Because the oscilloscope shows a graph of how the air pressure at the microphone varies with time.

Question 19

Characteristics of the speed of sound.

Answer 19

1. The speed of sound depends on the temperature of the air. Sound waves travel faster through hot air.
2. The speed of sound does not depend of the pressure of the air.
3. The speed of sound is different through different materials.

Question 20

How do you measure the speed of sound?

hard

Answer 20

If you make a sound and you set up two microphone with a set distance between each other. The microphone closest to the source triggers a timer, when the sound reaches the other microphone the timer stops. Dividing the distance between the microphones by the time take taken gives the speed of sound.

Question 21

How many Hz apart is each Octave?

Answer 21

Starts off as 64 Hz and doubles with each octave.

Question 22

Why do instruments differ in sound for the same octave?

Answer 22

Because weaker frequencies known as overtones that differ from instruments.

Question 23

What are the uses of ultrasound?

Answer 23

1. Cleaning and breaking e.g kidney stones or dislodging dirt from machinery.
2. Ships using echo sound to measure depth. (bats)
3. Metal testing in finding flaws in metals.
4. Scanning the womb for baby.