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GCSE Physics OCR B > P1 > Flashcards

P1 Flashcards

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1
Q

What is the difference between heat and temperature?

A

Heat measures energy in Joules, temperature measures how hot something is on a chosen or arbitrary scale, an average measurement of the kinetic energy of the particles in the object.

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2
Q

What does the amount of energy needed to raise the temperature of an object depend on?

A

The mass of the object, the change in temperature required and the material.

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3
Q

What is specific heat capacity?

A

The total amount of energy a material can hold (energy needed to raise 1kg of material by 1°C).

             energy transferred
      ---------------------------------------
mass x SHC x temperature change
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4
Q

Why doesn’t the temperature of a material change when it is changing state?

A

Temperature is a measure of kinetic energy, but when a material is changing state all the energy goes to breaking intermolecular forces so the particles don’t have more kinetic energy and the temperature stays the same.

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5
Q

What is specific latent heat?

A

The amount of energy required to melt or boil 1kg of material.
energy
——————
mass x SLH

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6
Q

How does fibreglass roof insulation work?

A

It prevents conduction and convection by trapping layer of air between fibres.

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7
Q

How does reflective wall foil work?

A

It prevents radiation by reflecting heat energy back into the room.

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8
Q

How does foam cavity wall insulation work?

A

It stops convection and conduction by trapping air in the foam.

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9
Q

How does double glazing work?

A

It stops conduction and convection by trapping air between the panes of glass.

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10
Q

How do draught excluders work?

A

They prevent conduction and convection by keeping as much warm air inside as possible.

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11
Q

How do you work out payback time?

A

cost of installation
Payback time = ————————-
(in years) annual saving

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12
Q

Why is trapped air a good insulator?

A

It has widespread particles so no conduction can happen and no convection can occur because the air can’t circulate.

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13
Q

How do you work out energy efficiency?

A

useful output energy
EE = —————————— X100
total input energy

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14
Q

What is conduction?

A

The transfer of heat energy through a substance by the vibrations spread through particles (kinetic energy).

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15
Q

What is convection?

A

The transfer of heat energy by the movement of particles: increased heat energy = more kinetic energy = expansion. The less dense gas or liquid rises, becomes cool again then falls.

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16
Q

What is radiation?

A

Heat transfer by electromagnetic waves.

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17
Q

What features does a transverse wave have?

A

Amplitude, wavelength, frequency (Hz), crest, trough.

18
Q

What types of waves are in the electromagnetic spectrum?

A 
Radio waves
Microwaves
Infrared waves
Visible light
Ultra violet
X-rays
Gamma rays
19
Q

How can you calculate the speed of a wave?

A

wave speed
———————–
frequency x wave length

20
Q

What is reflection?

A

When a wave is reflected off a surface.

21
Q

What is refraction?

A

When a wave speeds up or down when is travels through a different material, causing a change in direction.

22
Q

What is diffraction?

A

When a wave passes through a gap or opening and the edges spread out.

23
Q

How do you get maximum diffraction?

A

If the gap is the same size as the wavelength.

24
Q

When is light refracted?

A

If the angle of incidence is below the critical angle.

25
Q

What is wireless technology and what are it’s advantages?

A 
It is when waves from the electromagnetic spectrum are used to send information because they can be refracted and reflected.
Advantages:
24hr signals
No wiring needed
Portable items
26
Q

What are the advantages and disadvantages of using light as a signal?

A

Travels fast, small signal loss but can’t be used for wireless as it doesn’t diffract well

27
Q

What are the advantages and disadvantages of using electrical signals?

A

Can be sent along wires but signal deteriorates.

28
Q

What are the advantages and disadvantages of using radio waves as a signal?

A

Can be used for wireless since it diffracts well, but diffraction leads to signal loss.

29
Q

What are the properties of lasers?

A

Produce a beam of light in which all light waves have the same frequency, are in phase and have low divergence.

30
Q

How does a CD or DVD player work?

A

Pits are registered as 1’s because they reflect the light of a laser and non pits are 0’s.

31
Q

What does the amount of radiation emitted depend on?

A

Surface temperature, colour, texture

32
Q

What do microwaves do?

A

Penetrate 1cm into food, are absorbed by fat and water, cause burns in body tissue, travel through glass and plastics, are reflected by shiny metal surfaces.

33
Q

What do infrared waves do?

A

The heat the surface of food, reflected off shiny surfaces, absorbed by black objects.

34
Q

Which waves only travel/are transmitted in line of sight?

A

Microwaves

35
Q

How can microwave signals be lost and how can these problems be reduced?

A

Obstacles, poor weather, lots of water, the curvature of earth, interference.

Limiting distance between transmitter and receiver, placing the masts high.

36
Q

How is infrared radiation used?

A

Remote controls, sensors, wireless data links, burglar alarms.

37
Q

What is the difference between analogue and digital signals?

A

Analogue: vary in amplitude
Digital: only have two states
So interference is more of a problem for analogue.

38
Q

How can signals be transmitted around the curve of the earth?

A

Satellites or by reflected on the ionosphere.

39
Q

What is the difference between DAB and FM?

A

Both radio signals, DAB: more stations, less interference, not as good audio quality, not all areas can receive (shorter wavelength).

40
Q

What is the difference between P waves and S waves?

A

P waves: Longitudinal, travel through solids and liquids.

A waves: Transverse, solids only, slower, received in less places.

41
Q

What must scientists studying ozone make sure?

A

That their data is accurate: they will use new equipment, repeat experiments, consider other scientists ideas and test their theories based on current explanations.

42
Q

What rules wee introduced after the hole in the ozone layer was discovered?

A

Ban of CFCs, old fridges and freezers have to be disposed of properly.

GCSE Physics OCR B (6 decks)

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