5.1 + 5.2: Wave Behaviour + The EM Spectrum

Question 1

What are the two types of waves?

Answer 1

Transverse and Longitudinal

Question 2

What is a wave?

Answer 2

An oscillation that transfers energy from one place to another (doesn’t transfer any matter)

Question 3

What is a wavelength?

Answer 3

The distance of 1 entire oscillation

Question 4

Equation for the number of oscillations per second?

Answer 4

f = 1/T Frequency (Hz) = 1/time period (seconds)

Question 5

Equation to find the time it takes for 1 complete oscillation (period)?

Answer 5

T = 1/f Time period (sec) = 1/frequency (Hz)

Question 6

What is the time it takes for 1 complete oscillation called?

Answer 6

A period

Question 7

Wave speed equation?

Answer 7

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

Question 8

Describe the oscillations of a transverse wave

Answer 8

Oscillations are perpendicular to the direction of energy transfer

Question 9

Describe the oscillations of a longitudinal wave

Answer 9

Oscillations that are parallel to the direction of energy transfer

Question 10

Do transverse waves require a medium to travel through?

Answer 10

Not all transverse waves require a medium

Question 11

Do longitudinal waves need a medium to travel through?

Answer 11

All longitudinal waves need a medium to travel through e.g. air, a liquid or a solid

Question 12

What is the amplitude of a wave?

Answer 12

The maximum displacement of a point on a wave away from its un disturbed position

Question 13

What are the spread out areas on a longitudinal waves need called?

Answer 13

Rarefractions

Question 14

Transverse wave examples

Answer 14

All EM waves (e.g light and radio), waves of strings, sea waves, seismic S waves

Question 15

Longitudinal wave examples

Answer 15

Sound waves, seismic P waves

Question 16

Do EM waves vary in speed in a vacuum?

Answer 16

All electromagnetic waves travel at the same speed in a vacuum

Question 17

As the frequency increases, the wavelength…

Answer 17

…decreases

Question 18

Which EM wave has the largest wavelength?

Answer 18

Radio waves

Question 19

Which EM wave has the shortest wavelength?

Answer 19

Gamma rays

Question 20

Anything which has heat emits…

Answer 20

… EM waves in a range of frequencies called infrared waves

Question 21

What happens when objects absorb infrared waves?

Answer 21

They get hotter

Question 22

Dangers of radio waves

Answer 22

No known danger

Question 23

Dangers of microwave waves

Answer 23

Possible heat damage to internal organs

Question 24

Dangers of infrared waves

Answer 24

Skin burns

Question 25

Dangers of visible light waves

Answer 25

Bright light can cause eye damage

Question 26

Dangers of ultraviolet waves

Answer 26

Eye damage Sunburn Skin cancer

Question 27

Dangers of x-rays waves

Answer 27

Kills cells Mutations Cancer

Question 28

Dangers of gamma rays waves

Answer 28

Kills cells Mutations Cancer

Question 29

Uses of radio waves

Answer 29

Communication (radio and TV)

Question 30

Uses of microwave waves

Answer 30

Heating food Communication (Wi-Fi, phones, satellites)

Question 31

Uses of infrared waves

Answer 31

Remote controls Fibre optic communication Thermal imaging (medicine and industry) Night vision Heating or cooking things Motion sensors (for security alarms) Electrical heaters Infrared cameras

Question 32

Uses of visible light waves

Answer 32

Seeing and taking photos/videos Fibric optic communications

Question 33

Uses of ultraviolet waves

Answer 33

Security marking (fluorescence) Fluorescent bulbs Getting a sun tan

Question 34

Uses of x-ray waves

Answer 34

X-ray images (medicine, airport security, industry)

Question 35

Uses of gamma ray waves

Answer 35

Sterilising medical instruments Treating cancer

Question 36

Largest EM wavelength?

Answer 36

Radio 10^3m

Question 37

Smallest EM wavelength

Answer 37

Gamma Ray 10^-12m

Question 38

EM spectrum?

Answer 38

Gamma ray, X-ray, Ultraviolet, Visible Light, Infrared, Microwave, Radio

Question 39

Do EM waves form a continuous spectrum

Answer 39

Yes, they have no gaps

Question 40

What part of the EM spectrum can our eyes detect?

Answer 40

Visible light 0.5 x 10^-6

Question 41

How are radio waves produced?

Answer 41

They are produced by high-frequency alternating currents and induce similar currents when they are received

Question 42

1. A student is trying to calculate how far away they are from a large cliff. The student claps loudly once. After a short time, they hear a second clap. The second clap is quieter. i. Explain why they hear the second clap and why the second clap is quieter. (2)

Answer 42

The sound reflects/echoes (from the cliff) The amplitude of the sound decreases with distance / some of the energy /wave /sound is absorbed (by the cliff/air)

Question 43

Cooking using infrared in the conventional electric oven uses 20 times more energy than the microwave oven to cook the meal. Describe and explain how the meal is cooked in each oven and why they require such different cooking times.

Answer 43

Microwave : m.w. penetrate 1-2 cm / short distance into food m.w. absorbed by water / fat / sugar • this causes heating / particles gain energy • rest of food cooked by conduction / covection • m.w. reflected by sides of oven m.w. pass through (glass) dish. B. infrared cooking only heats the surface of the food infrared reflected by sides of oven rest of food cooked by conduction / convection idea of some infrared reflected from (glass) dish. C. comparison / explanation of longer or shorter cooking times • more food heated directly / at start in m.w. oven / ora • less food needs cooking by conduction / convection in m.w. oven / ora • energy of m.w. goes directly into food all of the oven / larger oven or space needs heating in conventional oven • greater energy need for i.r. method because of need to heat all of food / oven (space). Vase penetrate further in me than ir