Waves 🌊

Question 1

What are waves?

Answer 1

Waves transfer energy from one point to another through vibrations.

Question 2

What is a transverse wave?

Answer 2

In transverse waves the particles of the medium vibrate perpendicularly to the direction of wave flow.

Question 3

What is a longitudinal wave?

Answer 3

The particles of the medium vibrate parallel to the direction of wave flow.

Question 4

What waves are longitudinal?

Answer 4

Sound and ultrasound.

Question 5

What are some transverse waves?

Answer 5

Water waves and electromagnetic waves.

Question 6

What is frequency?

Answer 6

The frequency of a wave is the number of waves produced by a source each second.

It is measured in hertz (Hz).

Question 7

What is the wavelength?

Answer 7

The distance between a point on one wave and the same point on the next wave.

It is easiest to measure the wavelength from trough to trough or crest to crest.

Wavelength is measured in metres (m).

Wavelength is represented by λ.

Question 8

What is the amplitude of a wave?

Answer 8

The amplitude of a wave is its maximum displacement from its undisturbed position.

Question 9

What 2 ways can transverse and longitudinal waves be represented graphically?

Answer 9

1. Displacement of the particles against time. (Displacement/time graph).
2. Displacement of the particles against distance (Displacement/distance graph).

Question 10

What is the equation for velocity?

Answer 10

V=Fλ

Question 11

What is ultrasound and what is it used for?

Answer 11

It is the name given to sound frequencies greater than 20,000 Hz.

It is used in medicine to measure foetal head diameter and in industry to detect defects of metals.

Question 12

What is sonar?

Answer 12

The use of sound pulses to detect objects underwater.

Question 13

What is radar?

Answer 13

The use of reflected radio waves to track fast-moving objects such as aircraft and ships.

Question 14

What are the different regions of the electromagnetic spectrum, what is their order of wavelength and frequency?

Answer 14

Radio waves, microwaves, infrared, visible light, ultraviolet, x-ray, gamma rays.

They increase in frequency, and decrease in wavelength as you go up the spectrum.

Question 15

What is the speed of electromagnetic waves in a vacuum?

Answer 15

They all travel at the same speed in a vacuum.

Question 16

What are the uses and dangers of radio waves?

Answer 16

Uses: communication and radio entertainment.

Dangers: Large doses are believed to cause cancer, leukemia and other disorders (this has not been proven).

Question 17

What are the uses and dangers of microwaves?

Answer 17

Uses: heating up food, used for communications by sending information to and from satellites in space.

Dangers: They cause internal heating of body tissues and burns. The heat which is then released can damage or kill healthy cells.

Question 18

What are the uses and dangers of infrared?

Answer 18

Uses: detecting hot objects in the dark (Infrared cameras), used for cooking in toasters and grills, used in remote controls for TV, used in optical fibres for communication.

Dangers: Infrared from the Sun causes sunburn.

If cells absorb too much infrared radiation the heating will damage or kill the cells.

Question 19

What are the uses and dangers of visible light?

Answer 19

Uses: seeing objects, used in optical fibres such as endoscopes for seeing into patients bodies.

Dangers: Very intense visible light can damage the retina at the back of the eye.

Question 20

What are the uses and dangers of ultraviolet?

Answer 20

Uses: used for security coding of equipment, used in sunbeds.

Dangers: Can cause skin cancer by ionising cells under the skin’s surface.

Question 21

What are the uses and dangers of x-rays?

Answer 21

Looking at bones in the body.

Dangers: Can cause cancer if absorbed by cells as ionisation can occur.

Question 22

What are the uses and dangers of gamma rays?

Answer 22

Uses: used to kill cancer cells, kill bacteria in food, to sterilise medical equipment.

Dangers: Can cause cancer by damaging healthy cells if it is absorbed.