P5 - Waves in Matter

Question 1

What is an amplitude?

Answer 1

The displacement from the rest position to a crest or trough

Question 2

What is a wavelength?

Answer 2

A full cycle of the wave

Question 3

What is a frequency and what is it measured in?

Answer 3

• It is the number of complete waves passing a certain point per second
• It is measured in hertz (Hz)

Question 4

What is a period of a wave?

Answer 4

The number of seconds it takes for one full cycle

Question 5

How do vibrations travel in transverse waves?

Answer 5

-The vibrations are perpendicular to the direction the wave travels

Question 6

How do vibrations travel in longitudinal waves?

Answer 6

-The vibrations are parallel to the direction the direction the wave travels

Question 7

Can transverse waves travel through liquids?

Answer 7

They can travel on surface of a liquid but can’t travel through liquids

Question 8

How do longitudinal waves travel in the air?

Answer 8

The waves squash up and stretch out the arrangement of particles in the medium they pass through. They make compressions and rarefactions

Question 9

What is the wave speed equation?

Answer 9

Wave speed (m/s) = frequency (Hz) x wavelength (m)

Question 10

What are the properties of electromagnetic waves

Answer 10

• They are transverse waves
• They travel at the same speed through air or space
• They transfer energy from a source to an absorber
• They can be reflected by shiny surfaces

Question 11

How is the EM spectrum designed

Answer 11

From long wavelength with a low frequency which is not ionising to a short wavelength with high frequency which is ionising

Question 12

What can we detect from the spectrum?

Answer 12

With our eyes we can detect only a small part of this spectrum which is visible light in different colours.

Question 13

How are radio waves used for television and radio communication?

Answer 13

Alternating currents in electrical circuits cause charges to oscillate. This creates an oscillating electric and magnetic field which creates a radio wave

Radio waves cause charged particle to oscillate and if they are part of a circuit they induce an ac of the same frequency as the radio wave.

Question 14

How are microwaves used in satellite communications and what are microwaves used for?

Answer 14

They communicate to and fro satellite as they can pass easily through the Earth’s watery atmosphere
- Used for, cooking food, mobiles and satellite communication

There are different wavelengths of microwaves to cook and for satellites

Question 15

Describe the reflection and refraction of radio waves

Answer 15

-Waves with long wavelengths and low frequency indergo most refraction in the ionosphere

Question 16

Describe uses of infrared rays

Answer 16

• Heating
• Cooling
• TV remotes
• night vision

Question 17

How do optical fibres work?

Answer 17

They work by bouncing light off the sides of a very narrow core. The pulse of light enters the core at a certain angle at one end and is reflected again and again until it emerges at the other end

Question 18

What are optical fibres used for?

Answer 18

Telephone and internet cable and medical purposes to see inside the body

Question 19

What are the hazards and the uses of ultraviolet

Answer 19

The uses:
-Energy efficient lamps
-tanning salons
-counterfeit detections
The hazards:
- Causes damage to the DNA in skin cells
-Causes skin cancer
-Causes premature aging of skin

Question 20

What are the hazards and uses of x-rays

Answer 20

The uses:
-Medical imagery
-Security
The hazards:
-Cause cell damage
-Can cause mutations in cells which cause cancer

Question 21

What are the uses and hazards of Gamma Rays

Answer 21

Gamma rays are used to detect cancer with radiotracers and can kill cancer.
Hazards are that it can cause cancer

Question 22

How is it used in detecting fractures?

How is X-Ray used for medical imaging?

Answer 22

• The film is placed below the part of the body which is being X-rayed
• X-ray is transmitted through soft tissue but absorbed by bones
• This then causes the film to go white where the X-ray has not transmitted which shows the bones

Question 23

How is it used to see an image of a baby in the uterus?

How is Ultrasound used for medical imaging?

Answer 23

• Ultrasound can pass through the body but it is partially reflected at boundaries between tissues
• The reflections are processed by a computer to produce an image
• You can calculate the distance of the bounday when you know the speed of it and the computer knows how long the wave took to be reflected

Question 24

Which colour refracts the most and why?

Answer 24

Violet refracts the most and red refracts the least because violet has the shortest wavelength so then it refracts the most and it travels the slowest