Waves

Question 1

Give a way to minimise X-Ray exposure during a scan of a vehicle containing people?

Answer 1

The people should step out or wear protective gear

Question 2

Which type of EM wave is typically transmitted in optical fibres?

Answer 2

Visible light

Question 3

What is the doppler effect?

Answer 3

The change in wavelength observed due to the source

Question 4

In cool conditions, would the resistance rise or drop

Answer 4

Rise

Question 5

Is the resistance high or low in the darkness?

Answer 5

high

Question 6

Describe the direction of vibrations in a longitudinal wave

Answer 6

The vibrations are parallel to the direction of energy transfer

Question 7

Which type of EM wave has the highest frequency

Answer 7

Gamma rays

Question 8

Explain how an alternating current produces radio waves

Answer 8

Alternating current is made up of oscillating charges which produce oscillating electric and magnetic fields in the form of radio waves

Question 9

Explain how microwaves heat food

Answer 9

Penetrates a few centimetres into the food before being absorbed by the water molecules. The energy from the absorbed microwaves causes the food to heat up

Question 10

What are optical fibres used for in phone lines?

Answer 10

To carry data over long distances

Question 11

Are all EM waves transverse

Answer 11

Yes

Question 12

What are transverse waves

Answer 12

A wave in which the oscillations are perpendicular to the direction of energy transfer

Question 13

Amplitude, Wavelength and Frequency definitions

Answer 13

Amplitude (dB) = maximum displacement of a point on the wave from its undisturbed position

Wavelength (lamda) = distance between the same point on two adjacent waves

Frequency (Hz) = number of complete waves passing a certain point per second

Question 14

How to find the period of a wave in seconds

Answer 14

T = 1/f

T (period (s)) = 1/ f (frequency (hZ))

Question 15

True or False? All waves can be absorbed, transmitted or reflected

Answer 15

True

Question 16

true or false…all waves can be absorbed, transmitted or reflected?

Answer 16

true - what happens depends on the wavelength of the wave and the properties of the materials involved.

Question 17

What is the one simple rule for ALL reflected waves?

Answer 17

Angle of Incidence = Angle of Reflection

Question 18

what is the difference between specular and diffuse reflection?

Answer 18

specular happens when a wave is reflected in a single direction by a smooth surface.
diffuse reflection is when a wave is reflected by a rough surface and rays are scattered in lots of different directions.

Question 19

Which type of EM wave is typically transmitted in optical fibres

Answer 19

Visible Light

Question 20

State what type of EM radiation is used to send signals to satellites?

Answer 20

Microwaves

Question 21

Give two damaging effects that gamma rays can have

Answer 21

• cell damage
• cancer

Question 22

State the law of reflection

Answer 22

The angle of incidence is equal to the angle of reflection.

Question 23

How to find the Gradient of a Distance-Time graph

Answer 23

change in d/change in t

Question 24

How to find the Gradient of a Velocity-Time graph

Answer 24

change in v/change in t

Question 25

Velocity equation

Answer 25

V = S/T

Question 26

Velocity definition

Answer 26

the rate of change of displacement

Question 27

Scalar

Answer 27

A quantity with magnitude but no direction

Question 28

Vector

Answer 28

A quantity with magnitude and direction

Question 29

Accelaration equation

Answer 29

A = v-u/t V = final velocity U = initial velocity T = time

Question 30

Acceleration definition

Answer 30

The rate of change of velocity

Question 31

Critical angle equation

Answer 31

n = 1/sin C

Question 32

GPE equation

Answer 32

m x g x h

Question 33

GPE, equation triangle

Answer 33

Question 34

Transverse wave definition

Answer 34

the vibrations are perpendicular to the direction of the energy transfer. (e.g light)

Question 35

Longitudinal wave definition

Answer 35

the vibrations are parallel to the direction of energy transfer (e.g sound)

Question 36

Reflection

Answer 36

Reflection happens when light bounces off an even surface.

Question 37

Refraction

Answer 37

Refraction occurs when a wave slows down or speeds up at a boundary between two materials

Question 38

Law of Reflection

Answer 38

Angle of incidence = Angle of Refraction

Question 39

Efficiency percentage equation

Answer 39

(Useful energy output/ Total energy output) x 100

Question 40

Law of energy

Answer 40

Energy can not be created or destroyed, only transferred between energy stores.

Question 41

Mass symbol

Answer 41

m

Question 42

Mass units

Answer 42

kg

Question 43

Volume symbol

Answer 43

V

Question 44

Volume units

Answer 44

m^3

Question 45

Is distance a scalar or vector quantity?

Answer 45

Scalar

Question 46

What is density?

Answer 46

Density is given by ρ=m/V, where the ρ is the Greek letter rho, not a p

Question 47

What is the Pressure formula

Answer 47

pressure = force/area

Question 49

state the formula linking pressure, force and area

Answer 49

P = F/A