Waves

Question 1

Which wave in the electromagnetic spectrum has the shortest wavelength?

Answer 1

Gamma rays have the shortest wavelength.

Question 2

The diagram shows what would happen if waves of a short wavelength approach an obstacle.

What would be observed if the waves had a long wavelength?

Answer 2

Long wavelengths diffract more than short wavelengths.

Therefore the waves would bend around the obstacle more.

Question 3

What does the prefix m stand for?

Answer 3

m stands for milli

milli = x 10^-3

Question 4

Describe what is meant by gamma radiation.

Answer 4

• Gamma radiation is a wave in the electromagnetic spectrum
• Gamma rays have no mass or charge
• Gamma rays have a very short wavelength and a high frequency

Question 5

What happens to the speed of a ray of light as it goes from glass into air?

Answer 5

As a ray of light goes from glass into air, its speed increases.

(the light speeds up in a medium which is less optically dense)

Question 6

What does the prefix G stand for?

Answer 6

G stands for giga

giga = x 10⁹

Question 7

What is the unit for period?

(period of a wave)

Answer 7

The unit for period is seconds (s)

Question 8

What does the prefix n stand for?

Answer 8

n stands for nano

nano = x 10^-9

Question 9

What type of wave is a water wave an example of?

Answer 9

A water wave is an example of a transverse wave.

Question 10

What is being shown in this diagram?

Answer 10

This is diffraction - the bending of waves around an obstacle.

Question 11

What is the unit for wavelength?

Answer 11

The unit for wavelength is metres (m)

Question 12

Give one application of radio waves.

Answer 12

• Broadcasting
• Satellite transmissions
• Communications

Question 13

Give one use of visible light.

Answer 13

• photography
• illumination
  
  • car headlights
  • street lighting

Question 14

Give one use of gamma rays.

Answer 14

• sterilising food and medical equipment
• treating cancer
• medical tracers

Question 15

State one source of visible light.

Answer 15

Sources of visible light include:

• the Sun
• light bulbs
• anything hot enough to glow

Question 16

What type of wave is a sound wave an example of?

Answer 16

A sound wave is an example of a longitudinal wave.

Question 17

What is meant by the wavelength of a wave?

Answer 17

Wavelength is the distance between a point on one wave and the same point on the next wave.

Question 18

Give one use of X-rays.

Answer 18

• medical X-ray scans
• airport security scanners

Question 19

Does a ray of light always change direction when it undergoes refraction?

Answer 19

No - not always. A ray of light which enters a material at 90° to the surface will not change direction.

(e.g. middle ray in diagram)

Question 20

Name the three quantities shown in this formula.

Answer 20

v = speed

f = frequency

λ = wavelength

(λ is called ‘lambda’)

Question 21

Which wave in the electromagnetic spectrum has the longest wavelength?

Answer 21

Radio waves have the longest wavelength.

Question 22

What is the unit for speed?

Answer 22

The unit for speed is metres per second (ms^-1)

Question 23

What happens to the speed of a ray of light as it goes from air into glass?

Answer 23

As a ray of light goes from air into glass, its speed decreases.

(the light slows down in a medium which is more optically dense)

Question 24

What is meant by refraction?

(in terms of waves)

Answer 24

Refraction is the change of speed (of a wave) caused by entering a different medium (e.g. air to glass).

Question 25

Name the three quantities shown in this formula.

Answer 25

d = distance v = speed t = time

Question 26

What is meant by the **frequency of a wave**?

Answer 26

**Frequency** is the number of waves per second.

Question 27

Name an example of a **longitudinal wave**.

Answer 27

**Sound waves** are longitudinal waves.

Question 28

A ray of light exits a block of glass (as shown). Describe the path of the ray of light after it exits the glass.

Answer 28

The ray of light bends **away from the normal** as it exits the glass.

Question 29

What **type** **of wave** are **microwaves** an example of?

Answer 29

Microwaves are an example of **transverse waves**.

Question 30

In the diagram shown, what is the **dotted line** and what is important about where it is?

Answer 30

The dotted line is the **normal**. The normal is at **90° to the surface** of the medium.

Question 31

What does the prefix **M** stand for?

Answer 31

**M** stands for **mega** **mega** = **x 10⁶**

Question 32

Name the two quantities shown in this formula.

Answer 32

T = period f = frequency

Question 33

What is the **unit** for **distance?**

Answer 33

The unit for **distance** is **metres** (**m**)

Question 34

State a **detector** of **radio waves**.

Answer 34

An **aerial** is used to detect radio waves.

Question 35

What does the prefix **k** stand for?

Answer 35

**k** stands for **kilo** **kilo** = **x 10³**

Question 36

Give **one** use of **ultraviolet**.

Answer 36

* security marking * detecting forged bank notes * fluorescent lamps

Question 37

What does the prefix **µ** stand for?

Answer 37

**µ** stands for **micro** **micro** = **x 10^-6**

Question 38

What is the **unit** for **time?**

Answer 38

The unit for **time** is **seconds** (**s**)

Question 39

Which wave in the electromagnetic spectrum has the **least energy**?

Answer 39

**Radio waves** have the **least energy**.

Question 40

From the diagram shown, identify the **wavelength** of the wave.

Answer 40

**C** is the **wavelength**.

Question 41

From the diagram shown, identify the **amplitude** of the wave.

Answer 41

**D** is the **amplitude**.

Question 42

What do **all waves** in the electromagnetic spectrum have in common?

Answer 42

All waves in the electromagnetic spectrum **travel at the same speed** (the speed of light).

Question 43

What is meant by the **amplitude** of a wave?

Answer 43

The **amplitude** of a wave is the **height of the wave**.

Question 44

How is the **frequency** of a wave in the e.m. spectrum related to its **energy**?

Answer 44

The **higher the frequency** of a wave in the e.m. spectrum, the **more energy the wave has**.

Question 45

What **speed** do all **waves** in the **electromagnetic spectrum travel** at?

Answer 45

All waves in the electromagnetic spectrum travel at the **speed of light** - **3 x 10⁸ ms^-1**.

Question 46

Which wave in the electromagnetic spectrum has the **greatest energy**?

Answer 46

**Gamma rays** have the **greatest energy**.

Question 47

State a **detector** of **infrared radiation**.

Answer 47

* photodiode * phototransistor * thermistor * thermocouple

Question 48

In the diagram shown, what do the symbols **i** and **r** represent?

Answer 48

**i** = angle of incidence **r** = angle of refraction

Question 49

A ray of light enters a block of glass (as shown). Describe the path of the ray of light after it enters the glass.

Answer 49

The ray of light will bend **towards the normal** as it enters the glass.

Question 50

Give **one** use of **infrared**.

Answer 50

* thermal imaging * remote controls * security systems

Question 51

Name the **seven** different types of waves in the **electromagnetic spectrum**. Try to list them from **long λ** (wavelength) to **short λ**.

Answer 51

Radio **(long λ)** Microwaves Infrared Visible Ultraviolet X-rays Gamma rays **(short λ)**

Question 52

What is the **unit** for **frequency?**

Answer 52

The unit for **frequency** is **hertz** (**Hz**)

Question 53

What is meant by **diffraction**?

Answer 53

**Diffraction** is the **bending of waves** around an obstacle.

Question 54

Give **one** application of **microwaves**.

Answer 54

* cooking * mobile phone communications

Question 55

What is meant by the **period of a wave**?

Answer 55

The **period** of a wave is the **time taken** for **one wave** to pass.

Question 56

Complete the following sentence: All waves carry ...............

Answer 56

All waves carry **energy**.

Question 57

What is meant by the statement "A source of waves has a frequency of 16 Hz" ?

Answer 57

This means that there are **16 waves per second** generated by the source.