Waves

Question 1

2 types of waves

Answer 1

Transverse and lognitudinal

Question 2

wave

Answer 2

Transfer of energy from one place to another

Question 3

Transverse waves

Answer 3

Particles vibrate at right angles to the waves direction of travel (propagation)

Question 4

Longitudinal waves

Answer 4

Particles travel parallel to the wave direction of travel.

Question 5

frequency and period definitions

Answer 5

frequency - Number of waves produced each second. Measured in Hertz (Hz)

period - Time taken for one whole wave to pass a point in space.

Question 6

wave equation

Answer 6

V = f x λ

v = wave speed (m/s)
f = frequency (Hz)
λ = wavelength (m)

λ is pronounced ‘lambda’

Question 7

forms of light

Answer 7

Light rays
Reflection of light
lane mirror

Question 8

Refraction

Answer 8

is the bending of light as it travels between 2 different mediums with different refractive index.

n= Sinθx/ Sinθr

n = refractive index
θx = angle of incidence
θr = angle of refraction

Question 9

Name the six ways in which you can describe an image

Answer 9

Enlarged / diminished
Inversed / upright
Virtual / real

Question 10

How glasses work

Answer 10

we put lenses in the eyes to change the refraction.
Converging (concave) lenses help with long sight correction.

diverging (convex) lenses help with short sighted correction.

Question 11

Total internal reflection

Answer 11

When a light ray travels from a medium of high refractive index to a medium of low refractive index it will refract away from the normal.

Question 12

Critical angle

Answer 12

The incident angle that results in a 90 degree refraction is called the critical angle.

n = 1/Sinθc

n = refractive index
θc = critical angle

Question 13

Properties of electromagnetic waves

Answer 13

transverse waves
Can travel through a vacuum (don’t rely on vibrations)
are vibrations
Travel very high speed in a vacuum

Question 14

do electric fields have oscillating particles

Answer 14

no they have oscillating fields

Question 15

wavelength (electromagnetic waves)

Answer 15

wide range of wavelengths and frequencies

Question 16

direction (electromagnetic waves)

Answer 16

Direction of propagation of the wave; the direction the light travels. In a vacuum the speed of propagation is 3.0 x 10^8 m/s for all electromagnetic waves

Question 17

magnetic field

Answer 17

There are two linked oscillating fields which are at right angles to each other and at right angles to the direction of propagation.

Question 18

electromagnetic waves speed

Answer 18

3.0 x 10^8
same speed in air but slower in other materials eg in glass 2.5 x 10^8 m/s

Question 19

Uses of the EM spectrum

Answer 19

Radio: communication (Radio a TV)
RFID tags (radio frequency identification)

Micro-waves: Heating food
cell phone signals
satellites

Infrared (IR): Heating
remote controls
Alarms
thermal imaging

Visible: sight
photograhy/film
illumination

Ultra-violet (UV): sterilisation
forgery detection

x-ray: Medical imaging
Security scanning. e.g) airports

Gamma: Quality control
imaging
cancer treatment
food sterilisation

Question 20

Dangers of the EM spectrum

Answer 20

microwaves: heating of cells

Infrared: skin burns

UV: Damage cells, DNA, eyes
=> cancer or eyesight degradation

X-rays and Gamma:
Over exposure can cause DNA damage => mutation
General cell damage

Question 21

List the EM spectrum in order of wavelength largest to smallest

Answer 21

Radiowaves largest
Micro-waves
infrared
visible
ultra-violet
x-ray
gamma frequency smallest

Question 22

Sound waves

Answer 22

Are vibrations that allow energy to travel through a medium.

Question 23

Speed of sound is higher in denser materials (name three examples and their speeds)

Answer 23

Air = 330-350 m/s
Water = 1500 m/s
Steel = 3100 m/s

Question 24

what is the human hearing in hertz

Answer 24

20-20,000 Hz

Question 25

Other uses of ultra sound

Answer 25

Sonar
Medical imaging of soft tissues