Chapter 11 - Properties of Waves

Question 1

What are waves?

Answer 1

waves are a means of transferring energy from place to place

Question 2

Does this slinky represent a longitudinal or transverse wave?

Answer 2

Transverse

Question 3

Does this represent a transverse or longitudinal wave?

Answer 3

Longitudinal

Question 4

What is a transverse wave?

Answer 4

• One that oscillates at right angles to the direction in which the energy or wave is moving

Question 5

Name an example of a transverse wave

Answer 5

• light waves
• waves travelling on the surface of water

Question 6

What is a longitudinal wave?

Answer 6

• A longitudinal wave is one in which the oscillations, are along the direction in which the energy or wave is moving

Question 7

Name an example of longitudinal wave

Answer 7

Sound waves

Question 8

Label:

a) Peak
b) Trough
c) Wavelength
d) Amplitude

Answer 8

Question 9

What is the amplitude?

Answer 9

• Maxiumum movement of particles from their resting position caused by a wave

Question 10

What is the wavelength?

Answer 10

• Distance between a particular point on a wave and the same point on the next wave

Question 11

What is the frequency?

Answer 11

• Number of waves produced each second by a source
• Or the number passing a particular point each second

Question 12

What is frequency measured in?

Answer 12

Hertz (Hz)

Question 13

What is the period?

Answer 13

• The time it takes for a source to produce one wave

Question 14

what is the equation for frequency?

Answer 14

1

__________________

time period (s)

Question 15

what is the equation for time period?

Answer 15

1

frequency

Question 16

Calculate the period of a wave a frequency of 200 Hz

Answer 16

T = 1 / frequency

= 1/200

= 0.005

= 5 ms

Question 17

What is the equation for wave speed?

Answer 17

frequency x wavelength

Question 18

A tuning fork creates sound waves with a frequency of 170 Hz. If the speed of sound in air is 340 m/s, calucate the wavelength of the sound waves

Answer 18

wave speed = frequency x wavelength

340 = 170 x wavelength

340 = 170 x 2

= 2m

Question 19

Explain how a ripple tank works (6 points)

Answer 19

• Motor is turned on
• Wooden bar vibrates
• Creating a series of ripples on the surface of the water
• Light placed above the tank creates patterns
• Patterns of the water waves on the floor
• We can see how water waves are behaving through patterns

Question 20

In reflection, the angle of incidence is ……. to the angle of reclection

Answer 20

equal

Question 21

what happens to a wave when they strike a concave barrier?

Answer 21

• they become curved and are made to converge

Question 22

what happens to waves when they strike a convex barrier?

Answer 22

• they are made to diverge

Question 23

What is refraction?

Answer 23

• When waves change speed they change direction, when they cross a boundary between two substances with different densities

Question 24

What is an example of refraction?

Answer 24

waves through glass and air

Question 25

What is diffraction?

Answer 25

the process by which a beam of light or other system of waves is spread out as a result of passing through a narrow aperture or across an edge, typically accompanied by interference between the wave forms produced.

Question 26

Example of diffraction around an edge

Answer 26

radio waves that are diffracted as they pass over hills

Question 27

When light reflects from the surface of a plane mirror, the angle of incidence is ..................... the angle of refraction

Answer 27

equal to

Question 28

Calculate the wavelength (2)

Answer 28

- number of waves/cycles = 3.5 - 0.60 = 0.17 (m)

Question 29

The wavelength of a wave is 0.17m. Calculate the frequency of this microwave. [speed of microwave in free space = 3x10 to the 8 m/s²]

Answer 29

wave speed = frequency x wavelength wave speed / wavelength = frequency 3x10 to the 8 / 0.17 = 1.8x10 to the 9 1.8x10 to the 9 Hz

Question 30

Name the effect shown by the radio waves in diagram 1 (1)

Answer 30

- Diffraction

Question 31

Suggest why this effect is not shown by the microwaves in diagram 2 (2)

Answer 31

- microwaves not diffracted as much - diffraction (only seen) when size of barrier/gap comparable to wavelength - radio-waves have (much) longer wavelength than microwaves/RA;