P1 Flashcards

0
Q

Name 3 ways that heat can move

A

Radiation
Conduction
Convection

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1
Q

What are the laws of energy?

A

Energy is indestructible
It cannot be divided
It disapates
Cannot be destroyed only transferred

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2
Q

What is Conduction?

A

The process in which particles vibrate to pass on kinetic energy to neighbouring particles.

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3
Q

Why do metals conduct heat well?

A

Because there are free delocalised electrons available so they can conduct the heater faster throughout the metal.

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4
Q

Why are non metals not as good conductors?

A

Most don’t have free electrons therefore they warm slower so they are good insulators.

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5
Q

Why are solids good conductors of heat?

A

Becuase they are closely packed together so the energy is conducted quicker.

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6
Q

Why aren’t liquids and metals not good conducts?

A

This is becuase the particles aren’t held as tightly together so there are less collisions.

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7
Q

What is convention?

A

When more energetic particles move from a hotter region to a cooler one and take heat with them.

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8
Q

How do radiators heat a room?

A

They use Convection by heating the energy nearby and they then move to a cooler region.

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9
Q

How can you save energy in a house?

A

You use insulators which are expensive to install however they save money overall.

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10
Q

Name 4 ways of insulating a house.

A

Fitting loft insulation to stop Convection
Double glazing to take more time for Conduction
Silver foil to stop Conduction
And a cavity wall to slow convection

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11
Q

What would be the payback time if,
Cost of insulation was £60
Annual saving was £15?

A

15x4= 60

Therefore, it would take 4 years.

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12
Q

What are thermograms?

A

When you take an image of the heat inside. Like on police programs.

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13
Q

How does a microwave work?

A

The microwave creates the radiation which hits the food and makes it vibrate until it has conducted all the way through and cooked the food. It has a grill to stop microwaves escaping.

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14
Q

How do you calculate energy efficiency?

A

Useful energy
—————– X 100= x
Total energy

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15
Q

How do you know if a percentage calculation is incorrect?

A

If the answer is more than 100%

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16
Q

What is a sankey diagram?

A

A diagram that compares waste energy to useful energy.

17
Q

What are the stages of heating ice?

A

Ice warming- gaining energy
Ice melting- energy is being used to break bonds so temp doesn’t rise
Water warms
Water is boiling- energy used to break bonds so temp doesn’t rise
Steam gets hotter

18
Q

How do you calculate the energy in J (SHC)

A

SHC X Temp rise X mass that is heated (kg)=energy J/Kg oC

19
Q

What effect does a high frequency have on the penetrating power?

A

It makes it more penetrating

20
Q

What can waves pass through that particles cannot?

A

A vacuum

21
Q

Why can’t particles pass through a vacuum?

A

Becuase there are zero particles inside the vacuum so they can’t pass thorough.

22
Q

What are microwaves used for?

A

They are used for cooking and communication

23
Q

How do cooking microwaves work?

A

The microwaves carry energy.
The waves and penetrate about 1 cm into the food
The fat and water molecules absorb kinetic energy and start to vibrate.
They don’t escape from the front due to a metal grid that reflects

24
Q

How are microwaves used for communication?

A

They use line of sight and waves to travel long distances at the speed of light.
They are blocked by mountains and the curvature of the earth.

25
Q

What are the types of waves in the electromagnetic spectrum?

A
Radio waves
Microwaves 
Infrared radiation 
Visible light 
Ultraviolet radiation
X-rays 
Gamma-ray
26
Q

What is the speed of waves?

A

300,000 km/s

27
Q

What is infrared radiation used for?

A

Optical fibre communication

28
Q

What is Ultraviolet light used in?

A

They are used for sunbeds and increase risk of skin cancer

29
Q

What are X-rays?

A

It is the name given when highly penetrating rays that emitted high energy electrons when they struck metal.

30
Q

What are X-rays used for?

A

They are used in medical examinations.

31
Q

What are Gamma rays used for?

A

They are used in killing malignant cancer cells

32
Q

What is frequency?

A

How many waves there are a second

33
Q

What is the equation for the speed of a wave?

A

Speed of wave (v) = frequency x wavelength

34
Q

What are the three parts of 1 wavelength

A

Amplitude (loudness)
Trough
Crest

35
Q

What is rat?

A

RULER
ARROW
TOUCHING

36
Q

What is total internal reflection?

A

When the incident ray is greater than the critical angle

37
Q

What is total internal reflection used for?

A

When travelling thorough optical fibres.

38
Q

What do you need to get total internal reflection?

A

The medium outside must be less dense than material inside

It has to be greater than the critical angle

39
Q

What is refraction?

A

Changing the speed of a wave when going to a denser medium so it changes its direction