Waves Flashcards

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1
Q

Complete this sentence .
Waves transfer ____ and ____
without transferring _______.

A

Waves transfer energy and information
without transferring matter.

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2
Q

Define frequency and give its units

A

● The number of waves passing through a point per second.
● Hz (hertz)

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3
Q

Define wavelength

A

The distance between two adjacent peaks on a wave.

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3
Q

Define amplitude

A

● The maximum displacement of the wave from its equilibrium position.
● The distance between the centre of the wave and a peak

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4
Q

What is meant by the period of the wave?

A

The length of time it takes for one full wave to pass through a point

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5
Q

How can you calculate the wave speed?

A

● Wave speed (measured in metres per second) is equal to the product of the wavelength and the frequency of the wave.
● Wave velocity= f ×λ

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6
Q

State an equation linking frequency and
period of a wave

A
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7
Q

What is a longitudinal wave? Give some examples.

A

● Vibrations are parallel to the direction of energy transfer(wave)
● Examples include sound waves and earthquakes (seismic waves)

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8
Q

What is a transverse wave? Give some example

A

● A wave with oscillations that are perpendicular ( 90 degrees) to the direction of energy transfer.
● Examples include electromagnetic waves

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9
Q

Explain what is meant by “the doppler effect”

A
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10
Q

At what speed does an electromagnetic wave travel in a vacuum?

A
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11
Q

What types of waves are electromagnetic waves?

A

Transverse

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12
Q

What do electromagnetic waves
transfer?

A

Energy and Information

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13
Q

What are the four common properties of all
electromagnetic waves?

A

· They are all transverse waves
· They all transfer energy or information
· They all travel at the speed of light in vacuum
· They all can be reflected, refracted or diffracted

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14
Q

Which part of the electromagnetic spectrum has the longest wavelength?

A

Radio waves

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15
Q

Order the electromagnetic spectrum from the highest frequency to the lowest frequency.

A
  1. Gamma Rays
  2. X-Rays
  3. Ultraviolet
  4. Visible Light
  5. Infrared
  6. Microwaves
  7. Radio Waves
16
Q

What are the colours of the visible light spectrum?

A

Red, Orange, Yellow, Green, Blue, and Violet.

17
Q

a.Which colour has the highest frequency?
b.Which colour has the lowest frequency?
c.Which colour has the lowest wavelength?
d.Which colour has the highest wavelength?

A

a.Which colour has the highest frequency? Violet
b.Which colour has the lowest frequency? Red
c.Which colour has the lowest wavelength? Violet
d.Which colour has the highest wavelength? Red

18
Q

What are the uses of radio waves?

A

● For communication through radio
● Used for satellite transmissions

19
Q

What are microwaves used for?

A

● Cooking in microwaves ovens
● Communications
● Satellites

20
Q

Which part of the electromagnetic spectrum is used in cooking, thermal imaging and television remote controls?

A

Infrared

21
Q

Give examples of uses for visible light?

A

● Allows us to see (used for vision)
● Photography
● Optical Fibres (endoscope,communication)

22
Q

What part of the electromagnetic spectrum is used to for security marking and in fluorescent lamps?

A

Ultraviolet

23
Q

What are some uses of x-rays?

A

● Scanners at airports
● Medical x-ray machines

24
Q

What are the uses and disadvantages of gamma rays?

A

● Used to sterilise food and medical equipment
● Used in cancer diagnosis
But
Can cause mutations or damage to body cells.
This could lead to death.

25
Q

What are the disadvantages of microwaves?

A

They can cause heating of internal tissues in the body

26
Q

Which part of the electromagnetic spectrum is used in TV remotes and can also cause skin burns?

A

Infrared

27
Q

Does the danger that is associated with electromagnetic waves increase with frequency or with wavelength?

A

With frequency

28
Q

What are the dangers of excessive exposure to ultraviolet?

A

You could damage your eyes and the cells on the surface of your skin. This could lead to skin cancer or eye conditions.

29
Q

What is the normal (in terms of reflection and refraction)?

A

A vertical imaginary line which is perpendicular to the boundary.

30
Q

What happens when light is reflected off a boundary?

A

It is reflected (bounces) off a smooth flat surface so that the angle of incidence (the angle it comes in at) is the same as the angle of reflection (the angle it leaves at).

31
Q

What happens when light is refracted while passing through 2 different media?

A

● The light changes speed and direction in the new medium
● If the new medium is more dense, the light will travel slower and bend towards the normal
● If the new medium is less dense, the light will travel faster and bend away from the normal

32
Q

State an equation linking angle of incidence, angle of refraction and refractive index

A
33
Q

What is the critical angle?

A

The angle of incidence which causes the angle ofreflection to be 90 degrees so that that the light refracts onto the boundary.

34
Q

State an equation linking critical angle and refractive index

A
35
Q

What is total internal reflection?

A

When light is trying to pass from a less dense medium to a denser medium, it can be reflected back to the less dense medium if the angle of incidence is larger than the critical angle between two media.
This reflection is called Total Internal Reflection.

36
Q

State two uses of total internal reflection

A
  • Endoscopes
  • Periscopes
  • Optical Fibres
  • Cat Eye Reflectors
  • Shining of Diamonds
37
Q

If light hits a boundary at 90 degrees to the surface, will the light refract?

A

No it will not