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Physical Science > Electromagnetic Radiation > Flashcards

Electromagnetic Radiation Flashcards

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1
Q

Where in our lives do we use electromagnetic radiation

A

Broadcasts from tv stations, radio stations and orbiting satellites. Microwave ovens, a remote control to open a garage door, cell phones etc

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2
Q

What are water waves, waves in a string or spring and sound waves called

A

Mechanical waves

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3
Q

What do mechanical waves require that electromagnetic radiation does not require

A

A propagation medium

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4
Q

Why doesn’t electromagnetic radiation need a propagation medium

A

They propagate in an empty space

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5
Q

Why does electromagnetic radiation have a dual nature

A

It acts a wave and a particle

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6
Q

What is diffraction

A

The ending or spreading of waves around the edge of a barrier or opening

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7
Q

What is the photoelectric effect

A

It is an effect that showcases that light, and all electromagnetic radiation has particle properties

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8
Q

What is a photon

A

A particle of light. It is an energy packet of light

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9
Q

What is the source of electro magnetic radiation

A

The acceleration of electrical charges. Electric charges in motion cause a change in magnetic field

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10
Q

What is a changed magnetic field always accompanied by

A

A changed electric field That is perpendicular to the direction of the magnetic field

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11
Q

What are electromagnetic waves

A

Varying electrical and magnetic fields propagated in the form of waves

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12
Q

What are the seven main groups in the electromagnetic spectrum (in order)

A

Radio waves, micro waves, infrared, visible light (ROYGBIV), ultra violet, x-rays, gamma rays

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13
Q

What are the properties of electromagnetic waves

A
  • they are transverse waves
  • they move the same speed in a vacuum (3 x 10^-8 m.s^-1)
  • can move through a vacuum (don’t need a medium to propagate through)
  • they can move through mediums but it will move slower than in a vacuum
  • transfers energy from one place to another (when charges accelerate they radiate energy)
  • they undergo diffraction and interference
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14
Q

What are examples of radio waves

A

Radio, tv broadcasts, communication

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15
Q

What are the main sources of radio waves

A

Transmitting antenna as in radio and tv stations

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16
Q

What are the uses of micro waves

A
  • Micro wave ovens (they carry the energy to water molecules in food and heats it)
  • radar air control to determine the position of an aircraft
  • satellite communication
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17
Q

What is the main source of microwaves

A

Klystron

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18
Q

What are the uses of infrared waves

A
  • transfers energy or heat and gives us a feeling of warmth in our skins when we stand in front of a heater
  • used in thermal cameras
  • remote controls
  • navigation
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19
Q

What are the main sources infrared

A

Warm bodies like fires, sun

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20
Q

What are the uses of visible light

A
  • production of food by plants
    -to enable us to see things around us
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21
Q

What are the main sources of visible light

A

Sun, globes

22
Q

What are the uses of UV rays

A

-lighting
-optical illumination
- fluorescent pen (highlighter)
-detect forged bank notes
- bees use it because flowers stand out more at this frequency

23
Q

What are the main sources of UV rays

A

Sun, florescent lamps

24
Q

What are the main uses of X-rays

A

-medical imaging
-CT-scan
- security checks

25
Q

What are the main sources of X-rays

A

Discharged tubes

26
Q

What are the uses of gamma rays

A

-kills cancer cells
- sterilise food and equipment
- increase shelf life of food
- used to kill bacteria in marshmallows

27
Q

What is the main source of gamma rays

A

Radioactive elements

28
Q

What is the penetrating ability of visible light, UV rays, X rays

A

Visible light reflects on the human body,
UV rays (from the sun) damaged the skin, x rays are able to penetrate the skin and bone and allow for pictures inside the human body to be taken

29
Q

What affects the degree of penetration of electromagnetic radiation

A

The higher the frequency of the electromagnetic radiation the deeper the penetration

30
Q

What is ionising radiation

A

Dangerous radiation like UV rays, and x-rays, gamma rays

31
Q

What protects us from most electromagnetic radiation

A

The earths atmosphere

32
Q

What are the two different frequency ranges of UV light

A

UVA and UVB

33
Q

What are the negative effects of UVA and UVB

A

They can damage collagen fibres which result in ageing of skin, DNA damage and possibly skin cancer. Damage to eyes,

34
Q

How is UV Light used for tanning

A

The skin produces the brown pigment melanin as a protection against Uv rays.

35
Q

What makes a good UVB protection sunscreen

A

A sunscreen with Padimate O, Homosalate, Octisalate, Octinoxate

36
Q

What makes a good UVA protection sunscreen

A

Avbenzone

37
Q

What makes a good UVA And UVB protection sunscreen

A

Octocrylene, titanium dioxide, zinc oxide and mexoryl

38
Q

What are the negative effects of x rays

A

Cell damage and cancer

39
Q

What are the negative effects of gamma rays

A

They can change DNA, which can promote cancer

40
Q

What are the negative effects of cell phones and micro radiation

A

Cellphones have been linked to brain cancer (although there is no concrete proof to this)

41
Q

What does the wave model explain

A

It explains electromagnetic radiation as alternating electric and magnetic fields that oscillate perpendicular with the direction of movement and each other.

42
Q

What does quantisation mean

A

It means a quantity consists of quantities that cannot be made smaller

43
Q

What is a quantum

A

An indivisible amount of a physical quantity

44
Q

What are the assumptions that Max Planck made in 1901

A
  • energy is radiated in separate packets of energy that he calle do quanta
  • each quantum carries a certain amount of energy E which is equal to hf, where h is the universal constant 6,626 x 10^-34 and f is the frequency of the radiation
  • the quantity energy in each quantum is directly proportional to the frequency of the radiation
  • a quantum cannot be divided, you can only radiate and absorb an integer number quanta
  • this energy is propagated through space as electromagnetic waves
45
Q

What is the relationship between energy and the wavelength

A

Energy is inversely proportional to the wavelength

46
Q

How do different animals behave to impending natural distasters

A

Dogs growl or bite their owners
Sharks go deeper into the sea
Elephants trumpet louder and move to upland areas
Frogs gather in thousands and vacate
Rodents flee their hopes

47
Q

What is reflection and give an example

A

Waves Bouncing off a surface eg mirror

48
Q

What is refraction and give an example

A

Waves bending after penetrating water eg spoon in water

49
Q

What is the formula for momentum

A

P = mv

50
Q

What is the SI unit for momentum

A

Kg.m.s^-1

Physical Science (29 decks)

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