Waves

Question 1

Difference between longitudinal and transverse waves

Answer 1

Longitudinal : travel parallel to the direction of travel
Transverse : travel perpendicular to the direction of travel

Question 2

What is amplitude

Answer 2

The distance from the centre lin to the peak or trough of a wave

Question 3

What is frequency

Answer 3

The number of waves passing a certain point in a specific amount of time

Question 4

What is wavelength

Answer 4

The distance between two peaks

Question 5

What is wavefront

Answer 5

An imaginary surface representing points of a wave that are in the same points of their cycle

Question 6

What is the period of a wave

Answer 6

The time for one complete cycle

Question 7

what do waves transfer and what do they not

Answer 7

waves transfer energy and information

they don’t transfer matter

Question 8

what is the relationship between the speed, frequency and wavelength of a wave

Answer 8

wave speed = frequency x wavelength

Question 9

what is the relationship between frequency and time period

Answer 9

frequency = 1/time period

Question 10

what is the doppler effect

Answer 10

a change in the observed frequency and wavelength of a wave when its source is moving relative to an observer.

Ahead of the car wavefronts are compressed as the car is moving in the same direction as the wavefronts. This creates a shorter wavelength and a higher frequency.

Behind the car wavefronts are more spread out as the car is moving away from the previous wavefronts. This creates a longer wavelength and a lower frequency.

Question 11

explain that all waves can be reflected and refracted

Question 12

what spectrum is light part of

Answer 12

the electromagnetic spectrum

Question 13

list the electromagnetic spectrum in order of decreasing wavelength

Answer 13

radio waves
microwaves
infrared
visible light
ultraviolet
x-rays
gamma rays

Question 14

what are the components of visible light

Answer 14

V violet
I indigo
B blue
G green
Y yellow
O orange
R red

Question 15

when do all waves in the EM spectrum travel at the same time

Answer 15

in free space

Question 16

what is the use of radio waves

Answer 16

broadcasting and communicaions

Question 17

what is the use of microwaves

Answer 17

cooking and satellite transmissions

Question 18

what is the use of infrared waves

Answer 18

heaters and night vision equipment

Question 19

what is the use of visible light

Answer 19

optical fibres and photography

Question 20

what is the use of ultraviolet waves

Answer 20

florescent lamps

Question 21

what is the use of x-rays

Answer 21

observing the internal structure of objects and materials, including medical applications

Question 22

what is the use of gamma rays

Answer 22

sterilising food and medical equipment

Question 23

explain the detrimental effects of excessive exposure of the human body to microwaves and describe a simple protective measure against it

Answer 23

internal heating of body tissue

protective measure- reduce exposure

Question 24

explain the detrimental effects of excessive exposure of the human body to infrared light and describe a simple protective measure against it

Answer 24

skin burns

protective measure- reduce exposure

Question 25

explain the detrimental effects of excessive exposure of the human body to ultraviolet and describe a simple protective measure against it

Answer 25

damage to surface cells and blindness protective measure- reduce exposure

Question 26

explain the detrimental effects of excessive exposure of the human body to gamma rays and describe a simple protective measure against it

Answer 26

cancer, mutation protective measure- reduce exposure

Question 27

what are light waves and what can happen to them

Answer 27

light waves are transverse waves and they can be reflected and refracted

Question 28

what is the law of reflection

Answer 28

angle of incidence = angle of reflection

Question 29

how do you draw a ray diagram to illustrate reflection

Answer 29

draw an incident ray and a normal, angle of incidence is incidence ray towards normal draw the reflected ray and measure and angle of reflection which is ray of reflection towards normal

Question 30

how do you draw a ray diagram to illustrate refraction

Answer 30

draw an incident ray and a normal, angle of incidence is incidence ray towards normal draw a refracted ray which is bent towards the normal and the angle of refraction is from the ray of refraction towards the normal

Question 31

what apparatus is needed to investigate the refraction of light

Answer 31

rectangular blocks semi-circular blocks triangular prisms

Question 32

what is the relationship between refractive index, angle of incidence and angle of refraction

Answer 32

n = sin i / sin r

Question 33

describe the practical for investigating the refraction of light

Answer 33

1) shine a ray onto one of the sides of the glass block, so that the ray emerges on the opposite side of the block. mark the directions of both these rays with crosses 2) draw around the glass block before removing it 3) using the crosses, draw in the direction of both rays 4) draw in the direction of the ray that travelled inside the glass block 5) draw a normal line where the ray enters the block 6) measure the angle of incidence and angle of refraction 7) use the equation sin i / sin r to find the refractive index of the glass block

Question 33

what is the role of TIR in transmitting information along optical fibres and in prisms

Answer 33

it is used to transmit signals along optical fibres

Question 34

explain the meaning of the critical angle c

Answer 34

The angle of incidence which produces an angle of refraction of 90 (refracted ray is along the boundary of the surface). When the angle of incidence is greater than the critical angle, total internal reflection occurs (all light is reflected at the boundary). This effect only occurs at a boundary from a high refractive index material to a low refractive index material.

Question 35

what is the relationship between critical angle and refractive index

Answer 35

sin c = 1/n

Question 36

what are sound waves and what can happen to them

Answer 36

they are longitudinal waves and they can be reflected and refracted

Question 37

how can oscilloscope and microphone be used to display a sound wave

Answer 37

With the microphone plugged into the oscilloscope and a sound incident on the microphone, the microphone will transfer the sound into an electrical signal which the oscilloscope can display .The x axis show the time base which can be adjusted for example 2ms for 1 square so time period and frequency can be calculated from this, along the y axis voltage is displayed as the wave is converted into an electrical signal this means amplitudes can be compared.

Question 37

what is the frequency for human hearing

Answer 37

20 hz to 20,000 hz

Question 37

describe the practical to investigate the speed of sound in air

Question 38

how does the loudness of a sound relates to the amplitude of vibration of the source

Answer 38

The greater the amplitude the louder the sound. Bigger vibrations of a sting mean more energy is being put in so more energy out as sound waves.

Question 39

how does the pitch of a sound relate to the frequency of vibration of the source

Answer 39

High frequency means high pitch. If a string vibrates with a higher frequency then the note sounds higher.