Topic 2- Waves and the electromagnetic spectrum

Question 1

What is a amplitude, wavelength, frequency and period?

Answer 1

Amplitude- displacement from the rest position to a crest
Wavelength- length of the full cycle of the wave
Frequency- number of complete cycles passing a certain point each second
Period- number of seconds to complete one full cycles

Question 2

Explain transverse waves

Answer 2

Vibrations are perpendicular to the direction the wave travels. (have sideways vibrations)
e.g 
electromagnetic waves
s- waves
ripples and waves in water

Question 3

Explain longitudinal waves

Answer 3

In longitudinal waves vibrations are parallel to the direction the wave travels.
e.g
sound-waves
p-waves

Question 4

equation for wave speed

Answer 4

wave speed (m/s)=wavelength(m)X frequency(Hz)

Question 5

How do you measure the speed of sound ?

Answer 5

Firstly set up a signal generator to a speaker , to generate sounds with a specific frequency. Then you can use two microphones and an oscilloscope to find the wavelength of the sound generated.

Question 6

How do you measure the speed of the water ripples

Answer 6

Turn on a strobe light and and you will see a wave pattern in the tank form .The change the frequency until the pattern seems to freeze. Then measure the distance between each wavelength.

Question 7

How do you find out the speed of waves in solids?

Answer 7

1. Measure and record the length of the metal rod
2. Then set up your equipment such as elastic bands, hammer, microphone and clamps
3. Tap the rod with the hammer
4. Then write down the peak frequency that is displayed on the computer.
5. Then repeat this 3 times

Question 8

What does transmitted mean?

Answer 8

That it carries on travelling through the material

Question 9

What does refraction mean ?

Answer 9

Changing direction at a boundary

Question 10

What is the name of the angle between the normal and the ray?

Answer 10

Angle of incidence

Question 11

Explain how you hear sounds ?

Answer 11

The sound wave enters the ear and causes the eardrum to vibrate. These vibrations are transmitted through your ear and turned into electrical signals with are then sent to the brain

Question 12

What is ultra sound?

Answer 12

sound with frequencies higher that 20000hz

Question 13

What causes seismic waves?

Answer 13

earthquakes and explosions

Question 14

Explain p-waves inside the earth?

Answer 14

they are longitudinal and they travel through solids and liquids

Question 15

Explain s-waves inside earth?

Answer 15

they are transverse and only travel through solids

Question 16

What is specular reflection?

Answer 16

when waves are reflected in a single direction by a smooth surface.

Question 17

What is the law of reflection?

Answer 17

Angle of incidence= Angle of reflection

Question 18

Describe an experiment you could use to measure how much light is refracted when it enters a glass block ?

Answer 18

1. Draw around the glass of block onto a piece of paper
2. Then shine the light ray at it from a ray box
3. Then mark the incident ray and mark where the ray emerges from the block, then remove the block and join up the lines
4. The measure the angle of incidence and the angle of refraction.

Question 19

What are opaque objects?

Answer 19

Objects that do not transmit light.

Question 20

Explain why a cucumber looks green?

Answer 20

because it reflects green but absorbs all the other wavelength

Question 21

What colour would a cucumber look if it went through a red colour filter.

Answer 21

black

Question 22

Principal of a converging lens

Answer 22

the point where rays hitting the lens parallel to the axis meet

Question 23

Principal of diverging lens

Answer 23

the point where light rays hitting the lens parallel to the axis appear to come from

Question 24

What type of lens does a divergent lens produce?

Answer 24

Virtual

Question 25

Colours from the longest wavelength to the shortest

Answer 25

Red
Orange
Yellow
Green 
Blue
Indigo 
Violet

Question 26

Draw the em spectrum

Answer 26

on card 12

Question 27

What causes the overall temperature of the earth to change

Answer 27

It depend on the amount of radiation it reflects, absorbs and emits.

Question 28

Explain how you could investigate how well different surfaces emit radiation

Answer 28

1. Wrap four identical test tubes with four different colours
2. Then boil the kettle , and fill each test tube with the same amount of water
3. Then use a thermometer to measure the temperature of the water every minute.
   - you will find that the ones that have decreased temperature quicker emit more radiation

Question 29

How can radio waves be made

Answer 29

by oscillating charges

Question 30

What are radio waves mainly used for?

Answer 30

communications and broadcasting

Question 31

What are microwaves and radio waves used for

Answer 31

satellites

Question 32

Three uses of infrared radiation

Answer 32

cooking, short range communications and thermal imaging

Question 33

What can infrared be used for

Answer 33

to increase or monitor temperature and to transfer information such as sending files between mobile phones

Question 34

What is ultraviolet used for

Answer 34

its used in fluorescent lamps , and bank notes

Question 35

What are x-rays used for?

Answer 35

They are used to view internal structures of our bodies and objects and can also be used in airport security scanners

Question 36

What are gamma rays used for\/

Answer 36

Used for sterilising things- like food and medical instruments
Also can be used to detect cancer