P1 5 Waves

Question 0

Transverse waves:

Answer 0

• Transverse waves vibrate at right angles to the direction of the energy transfer of the waves • All electromagnetic waves are transverse waves

Question 1

What are waves used for?

Answer 1

Waves are used to transfer energy and information.

Question 2

Longitudinal waves:

Answer 2

• Longitudinal waves vibrate parallel to the direction of the energy transfer of the waves • An example of a longitudinal wave is a sound wave

Question 3

Mechanical waves:

Answer 3

Mechanical waves need a medium to travel through, these waves may be transverse or longitudinal. Examples of mechanical waves are sound, water and seismic waves.

Question 4

What is the amplitude of a wave?

Answer 4

The amplitude of a wave is the height of the wave crest or the depth of the wave trough from the position at rest. The bigger the amplitude of the wave, the more energy the wave carries.

Question 5

What is the wavelength of a wave?

Answer 5

The wavelength of a wave is the distance from one wave crest to the next wave crest.

Question 6

What is the frequency of a wave?

Answer 6

The frequency of a wave is the number of wave crests passing a point in one second.

Question 7

Wave speed equation:

Answer 7

Wave speed (m/s)= frequency (Hz) x wavelength (m).

Question 8

What is the normal on a mirror?

Answer 8

The normal at a point on a mirror is a line drawn perpendicular to the mirror.

Question 9

Reflection of a light ray by a plane mirror:

Answer 9

• The angle of incidence is the angle between the incident ray and the normal • The angle of reflection is the angle between the reflected ray and the normal

Question 10

What does the law of reflection state?

Answer 10

The angle of incidence= the angle of reflection.

Question 11

What is refraction?

Answer 11

Refraction is the change of direction of a wave when it travels across a boundary.

Question 12

When a light ray refracts from air into glass (less dense to more dense medium), what happens?

Answer 12

The angle of refraction will be less than the angle of incidence, as it refracts TOWARDS the normal.

Question 13

When a light ray refracts from glass to air (more dense to less dense medium), what happens?

Answer 13

The angle of refraction will be greater than the angle of incidence as the light ray will refract AWAY from the normal.

Question 14

What is diffraction?

Answer 14

Diffraction is the spreading out of waves when they pass through a gap or round the edge of an obstacle.

Question 15

Fill in the missing word: The narrower a gap, the … the diffraction is.

Answer 15

Greater.

Question 16

Why do some people receive poor radio and TV reception?

Answer 16

If the radio waves do not diffract enough when they go over hills, the reception will be poor.

Question 17

Example of a use of diffraction:

Answer 17

Diffraction of ultrasonic waves is an important factor in the design of an ultrasonic scanner. The ultrasonic waves spread out from a hand-held transmitter and reflect from the tissue boundaries inside the womb.

Question 18

What is the frequency range of the normal human ear?

Answer 18

The range is 20Hz-20000Hz.

Question 19

What are sound waves?

Answer 19

Sound waves are vibrations that travel through a medium (substance). They cannot travel through a vacuum (space).

Question 20

How do echoes occur?

Answer 20

Echoes are due to sound waves being reflected from a smooth and hard surface.

Question 21

What will happen if sound approaches a wall covered in soft fabric?

Answer 21

The soft fabric will absorb the sound instead of reflecting it.

Question 22

What happens if the ‘loudness’ of a sound is increased?

Answer 22

The amplitude of the wave will increase too.

Question 23

What will happen if the frequency of a sound is increased?

Answer 23

The pitch of the wave will increase too.

Question 24

How are sound waves produced by an instrument?

Answer 24

Vibrations created in an instrument when it is played produces sound waves.

Question 25

Transverse Diagram

Answer 25

Question 26

Longitudinal Diagram

Answer 26

Question 27

Wave Diagram:

Answer 27

Question 28

Law of reflection:

Answer 28

Question 29

Refraction of light:

Answer 29

Question 30

Diffraction Diagram:

Answer 30