Physics - Core Flashcards

0
Q

Why are metals good conductors?

A

They have free electrons which pass the current on by vibrating against other free electrons and ions/atoms they collide more often making the current go through quicker

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1
Q

What is conduction?

A

The process of vibrating particles passing on their kinetic energy to neighbouring particles

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2
Q

Name the three ways in which heat energy can be transferred

A

Radiation, conduction and convection

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3
Q

Explain the green house effect

A

Th sun produces short wavelengths that can pass through the atmosphere and heat objects, but the heated objects produce long wavelengths that cannot escape the atmosphere heating the earth up

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4
Q

What is the u-value?

A

The rate at which heat can transfer through a material

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5
Q

What is specific heat capacity?

A

Show us how much energy a substance can store

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6
Q

What are the factors that increase the rate that a object can be heated up?

A
  • the temperature difference
  • the material that it is in contact with
  • shape
  • surface area
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7
Q

How does a vacuum flask keep insulated?

A

Double walled - prevents conduction convection
Silver walls - prevent heat loss be radiation
Insulating foam - conduction
Stopper - reduces heat transfer

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8
Q

What is convection?

A

The movement of particles in a fluid

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9
Q

What happens in a convection current?

A

The particles in the hotter region have more energy and move faster so therefore diffuse and become less dense, they rise above the cooler ones which have little energy and are sinking they then get heated again, this is a convection current

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10
Q

Explain the kinetic theory

A

Solids - strong attraction forces which keeps them in regular arrangement little energy so vibrate in fixed positions
Liquid- weaker attraction forces but still close together, have some energy that lets them move in random directions and pass each other at slow speeds
Gas - no attraction forces, lots of energy so pass each other at high speeds in random directions

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11
Q

Explain the process on condensation

A

Gas cools so Particles loose energy Get denser and come together as there no longer able to overcome the attraction forces and then becomes a liquid

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12
Q

Explain the process of evaporation

A

The particles have enough energy and are going fast enough to leave the liquid but they must be going in the right direction
They leave the liquid lowering the average kinetic energy and temperature so the liquid cools

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13
Q

List types of energy that cannot be stored 6

A
Kinetic
Light 
Sound
Thermal
Electrical
Nuclear
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14
Q

Name the three types of energy that can be stored

A

Chemical
Elastic potential
Gravitational potential

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15
Q

What is the conservation of energy principle?

A

Energy can be stored, dissipated or change from one form to another, but never can it be created or destroyed

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16
Q

What is useful energy

A

Energy that is where we want it in the form that it is wanted

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17
Q

What happens to wasted energy?

A

It dissipates into the surroundings

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18
Q

Why can no machine be more than 100% efficient?

A

Because you cant get more out than what you put in

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19
Q

Name the 4 non renewable sources of energy

A

Oil
Natural gas
Coal
Nuclear fuel

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20
Q

Name the 8 renewable sources of energy

A
Food
Wind
Solar
Wave
Hydroelectric
Geothermic 
Biofuels
Tide
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21
Q

What does a step up transformer do?

A

Increases voltage and lowers current

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22
Q

What does a step down transformer do

A

Decreases voltage and increases current

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23
Q

What happens to the carbon in carbon capture and storage?

A

Goes to gas fields and oil fields

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24
Q

Give impacts that non renewable energy sources cause

A
Oil spillages
Quarrying ruins landscapes
Sulfur dioxide
Pollution 
Nuclear waste
25
Q

Name the waves in the electromagnetic spectrum

A
Radiowaves
Microwaves
Infrared
Visible light
Ultraviolet 
X- rays 
Gamma rays
26
Q

What happens in optical fibres?

A

Infrared and visible light waves carry data over long distances, pulses of light are reflected of the sides of a narrow core from one end of the fibre to the next
+safer as it stays in fibre
+ more data is passed through

27
Q

How is visible light used in a camera?

A

Light film sensor
Aperture controls how much light is let in
Shutter speed controls how much time the light is exposed to the film

28
Q

Whats the difference between microwaves and radio waves?

A

Microwaves are shorter and dont spread out as much so they can pass through the earths atmosphere

29
Q

What is the doppler effect?

A

The doppler effect is the change in wavelength and frequency of waves from a moving source towards or away from the viewer
Towards: increased frequency and shorter wavelength
Away: decreased frequency and longer wavelength

30
Q

What is cosmic background radiation?

A

High gamma radiation that was left after the big bang

31
Q

What is red-shift?

A

An increase in the wavelength of electromagnetic waves from a star or galaxy due to its motion away from us, the faster the speed the greater the wavelength

32
Q

What is blue-shift?

A

A decrease in the wavelength of electromagnetic waves emitted from a star or galaxy due to its motion towards us, the faster the speed the shorter the wavelength

33
Q

How does red-shift prove the big bang theory?

A

It shows that everything should have come from an original place if everything is expanding away from something

34
Q

What is refraction?

A

The change in direction of a wave when it passes through a boundary of two substances

35
Q

What is diffraction?

A

The spreading out of waves as it passes through a gap or an object

36
Q

Name transverse waves

A

Electromagnetic waves
Ripples on water
Slinky spring
Waves on a string

37
Q

Name some longitudinal waves

A

Sound waves
Ultra sound
Pushing the end of a slinky

38
Q

What is the law of reflection?

A

The angle of reflection= angle of incidence

39
Q

Why do electric storage heaters usually contain concrete or bricks?

A

The concrete and bricks have a high specific heat capacity so can store a lot of energy

40
Q

Give ways in to increase the rate at which a gas condenses on to a surface

A

Increase density of the gas
Decrease temperature of the gas
Decrease temperature of the surface the gas touches
Increase the concentration of the gas by reducing airflow

41
Q

Why can some particles evaporate from a liquid at a temperature lower than a liquids boiling point?

A

The particles in a liquid all have different kinetic energies, high energy particles that are near the surface of the water and are travelling in the right direction can have enough energy to escape the liquid and form a gas

42
Q

How does cavity wall insulation help reduce heat loss?

A

Foam inserted into the gap will stop air from moving and forming convection currents

43
Q

How does reflection work?

A

The light bounces off and in to our eyes

44
Q

When/ how do you get a clear reflection?

A

When the light is travelling in the same direction and reflects from an even surface at the same angle

45
Q

What are sound waves caused by?

A

Sound waves are caused by vibrating objects

46
Q

Why can’t sound waves travel in space?

A

Because space is a vacuum and therefore there is no particles for the vacuum to vibrate off

47
Q

What is a frequency?

A

The number of compete waves passing a certain point per second

48
Q

What are the vibrations of a transverse wave?

A

In a transverse wave the waves are perpendicular at 90 degree angle to the direction of the energy transfer of wave

49
Q

What are the vibrations of a longitudinal wave?

A

The vibrations are parallel to the direction of energy transfer of the wave

50
Q

What happens when a wave goes from air to glass?

A

The wave goes toward the normal and the angle of refraction is smaller than the angle of incidence

51
Q

What happens to a wave when it goes from glass to air?

A

The wave goes away from the normal and the angle of refraction is bigger than the angle of incidence

52
Q

What makes diffraction bigger?

A

reducing the size of the gap and the gap between the waves/ wavelength

53
Q

How does the doppler effect work?

A

When the object is moving towards you there is an increase in frequency and the wavelength is shorter, whereas when the object is moving away from you than the frequency is decreased and there is a longer wavelength

54
Q

What happens when infrared is absorbed by the body?

A

It heats cells up and damages them

55
Q

What are microwaves used for?

A

Satellite communication and mobile phones

56
Q

What are the disadvantages for renewable sources?

A

Expensive
Not always reliable - wind
Only a small percentage of energy

57
Q

How does a bungee jump work?

A

GPE>KE>EP>GPE+KE

58
Q

Why do solar panels have matt black surfaces?

A

Matt black surfaces are the best absorbers therefore increase the rate of energy transfer

59
Q

Why are insulators bad conductors?

A

They have large spaces between there particles this would reduce and slow the rate of energy transfer