Waves

Question 1

amplitude

Answer 1

• the maximum displacement of a wave from its undisturbed (equilibrium) position

Question 2

angle of incidence

Answer 2

• angle between the incident ray and the normal

Question 3

black

Answer 3

• an object will appear black if it absorbs all wavelengths of radiation incident on it

Question 4

colour filters

Answer 4

• filters that absorb certain wavelengths and transmit others
• e.g. a blue filter will absorb all wavelengths other than those in the blue region of the colour spectrum

Question 5

colour

Answer 5

• determined by frequency and wavelength

Question 6

constant temperature

Answer 6

• a body remains at a constant temperature of it is absorbing radiation at the same rate that it is emitting it

Question 7

convex lens

Answer 7

• a lens that brings parallel rays to focus at the principal focus
• the image formed can be either real or virtual

Question 8

diffuse reflection

Answer 8

• reflection from a rough surface
• results in scattered light rays

Question 9

echo sounding

Answer 9

• technique that uses high frequency sound waves to detect objects deep in water and to measure the depth of water

Question 10

electromagnetic waves

Answer 10

• transverse waves that transfer energy form the source of the waves, to an absorber
• they form a continuous spectrum of different frequencies
• all travel at the same speed in a vacuum

Question 11

focal length

Answer 11

• the distance between the centre of a lens and its principal focus

Question 12

frequency

Answer 12

• the number of waves passing a given point in a second
• inverse of the wave’s period

Question 13

hertz

Answer 13

• unit of frequency

Question 14

human hearing

Answer 14

• humans can hear sounds in the frequency range of 20Hz to 20kHz

Question 15

infrared radiation

Answer 15

• type of radiation that all objects emit and absorb
• the hotter an object is, the greater the infrared radiation it emits in a given time

Question 16

infrared

Answer 16

• used for cooking food
• used for electrical heaters
• used for infrared imaging

Question 17

ionising radiation

Answer 17

• radiation that can cause the mutation of genes and cause cancer
• x-rays and gamma rays are both forms of ionising radiation

Question 18

lens

Answer 18

• an object that forms an image through the refraction of light

Question 19

longitudinal waves

Answer 19

• waves with oscillations that are parallel to the direction of travel/energy transfer

Question 20

magnification

Answer 20

• ratio of the image height over the object height for a lens
• it has no units

Question 21

microwaves

Answer 21

• used for satellite communications
• used for cooking food

Question 22

normal

Answer 22

• the normal is an imaginary reference line that is constructed perpendicular to a boundary at the point that the wave intercepts it

Question 23

p-waves

Answer 23

• longitudinal seismic waves that travel at different speeds through solids and liquids

Question 24

perfect black body

Answer 24

• an object that absorbs all radiation incident on it
• does not reflect or transmit any type of radiation

Question 25

period

Answer 25

- the time it takes for one complete wave to pass a given point - it is the inverse of frequency

Question 26

radiation dose

Answer 26

- a measure of the risk of harm to the body as a result of radiation exposure

Question 27

radio waves

Answer 27

- used for television and radio signals - they can be produced by oscillations in electrical circuits

Question 28

reflection

Answer 28

- when a wave bounces off a boundary - angle of incidence is always equal to the angle of reflection

Question 29

s-waves

Answer 29

- transverse seismic waves - cannot travel through liquid, only solids

Question 30

seismic waves

Answer 30

- waves produced by earthquakes

Question 31

sound waves

Answer 31

- longitudinal waves responsible for sound - in solids, sound waves are transmitted by the vibrations of the solid’s particles

Question 32

specular reflection

Answer 32

- reflection from a smooth surface in a single direction

Question 33

transverse waves

Answer 33

- waves with oscillations that are perpendicular to the direction of travel/energy transfer

Question 34

ultrasound scanning

Answer 34

- technique involving ultrasound waves being transmitted and then partially reflected at a boundary before being detected by a detector - time between transmission and detection can be used to calculate distances and built up an image

Question 35

ultrasound waves

Answer 35

- waves that have a frequency higher than the upper limit of human hearing - >20kHz

Question 36

ultraviolet

Answer 36

- used in energy efficient lamps and for sun tanning

Question 37

visible light

Answer 37

- only type of electromagnetic radiation that our eyes can detect - used for fibre optic communications

Question 38

wave speed

Answer 38

- speed at which energy is transferred through the medium - equal to the product of wavelength and frequency

Question 39

wavelength

Answer 39

- distance form a point on one wave to the same point on the adjacent wave

Question 40

white

Answer 40

- object will appear white if it emits all wavelengths equally