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Flashcards in P1 Deck (57):
0

How is heat energy measured?

- Joules (J)

1

What is happening if an objects temperature rises?

- The object is taking in heat energy

4

What is happening if an objects temperature drops?

- the object is giving out heat energy

5

What 3 things does the energy needed to raise the temperature of an object depend on?

- the objects mass
- the change in temperature required
- the objects material

6

How do you calculate the amount of energy supplied?

Total energy supplied=

Energy supplied per second ✖️ number of seconds

7

What is Specific heat capacity?

- the value of how much energy an object can hold

- the energy needed to raise the temperature of 1kg of material by 1 degree

8

How do you calculate the amount of energy needed to raise the temperature of an object?

Energy =

Mass(kg) ✖️ SHC(j/kg) ✖️ temperature change

9

How to you calculate specific heat capacity?

Specific heat capacity =

Energy ➗ (mass ✖️ temperature)

10

During the melting and boiling of water, what is the energy supplied used to do?

- to break intermolecular bonds as the water molecules change state.

11

What is Specific Latent Heat?

- the amount of heat energy required to melt or boil 1kg of a material

12

What doses specific latent heat depend on?

- the material
- the state

13

How do you calculate the energy required to boil or melt a certain mass of a material?

Energy = mass(kg) ✖️ specific latent heat

14

How do you calculate the payback time of an insulator?

Pay back time (years) =

Cost of product ➗ annual saving

15

What is a cavity wall?

- made up of an inner and outer wall with a cavity (space) full of air between them

16

How can heat loss be reduced from a cavity wall?

- by filling the space with air

17

What is energy efficiency?

- A measurement of how good an appliance is at converting input energy into a useful output energy

18

How can energy efficiency be calculated?

Efficiency=

(Useful out put energy ➗ total input energy) ✖️ 100

19

What are the 3 ways that heat energy can be trNsferred?

- conduction
- convection
- radiation

20

What is conduction?

- the transfer of heat energy through a substance from a hotter region to a cooler region without any movement of the substance itself

21

Why are metals very good conductors?

- because they have free electrons which can move through the material carrying energy

22

What is convection?

- the transfer of heat energy from hotter regions to cooler regions by the movement of particles

23

What type of wave is light?

- transverse wave

24

What are the 3 features of a transverse wave?

- Amplitude:
> the maximum disturbances caused by the wave
- Wavelength:
> the distance between each wave
- Frequency:
> the number of waves produced per second

25

What is the Electromagnetic spectrum?

- A continuos spectrum that extends beyond each end of the visible spectrum of light

26

What is the sequence of the Electromagnetic spectrum?

Radio waves ➡️ Microwaves ➡️ Infrared rays ➡️

Visible light ➡️ Ultraviolet rays ➡️ X-rays ➡️

Gamma rays

27

How can you calculate the speed of a wave?

Wave speed=

Frequency ✖️ wavelength

28

What speed do all electromagnetic waves travel at in a vacuum

- the same speed

29

What is diffraction?

- when the edges of a wave spread out as it passes through a gap or an opening

30

What is maximum diffraction?

- when the gap is the same width as the wavelength of the wave passing through it

- causes quality of image to reduce

31

When can light and infrared rays be reflected or refracted?

- when they cross a glass-air boundary

32

What does reflection and refraction depend on?

- the Angle of incidence

> if the angle is below the critical angle, the light or infrared is refracted away from the normal

> if the angle is above the critical angle the ray in totally internally reflected and not refracted

33

What are optical fibres and what are they used for?

- Long, flexible, transparent cables of a very small diameter

- used to send information in the form of pulses of light, or infrared radiation

- pulses aren't refracted, they are totally internally reflected

34

What is Electromagnetic radiation ?

- wireless technology

- used to send information without optical fibres

35

What is light used for communication produced by?

- a laser

36

What are the advantages and disadvantages of using Light to send information?

- advantages:
> travels very fast
> small loss of signal

Dissadvantages:
> can't be wireless

37

What are the advantages and disadvantages of using Electrical to send information?

Advantages:
> can be sent along wires

Disadvantages:
> signal deteriorates

38

What are the advantages and disadvantages of using Radio waves to send information?

Advantages:
> can be wireless

Disadvantages:
> diffraction leads to signal loss

39

What are some uses of lasers?

- surgery
- dental treatment
- cutting materials
- weapon guidance
- laser light shows

40

What are the waves like in laser light?

- all:
> have the same frequency
> are in phase with eachother
> have low divergence

41

What does 'in phase mean'?

- all the peaks and troughs match up

> waves in phase transfer a lot of energy

42

What does the amount of radiation that is absorbed or emitted from a surface depend on?

- surface temperature
- colour- black is good, white and silver are poor
- texture - dull is good, shiny is poor

43

What are the abilities of microwaves?

- are absorbed by water and fat molecules which causes them to heat up
- can penetrate about 1 cm of food
- can cause burns when absorbed by body tissue
- can travel through glass and plastics
- are reflected by shiny metal surfaces

44

What are the abilities of Infrared rays?

- used to heat the surface of food in cooking
- reflected of shiny surfaces
- absorbed by black objects

45

What can cause microwave signals to be lost or affected?

- large objects blocking the signal
- poor weather
- the curvature of the Earth
- interference between signals

46

What are infrared rays used in? (5)

- remote controls
- sensors for doors
- short distance wireless data links for computers or phones
- burglar alarms ( detecting body heat)
- security lights

47

What are Analogue signals?

- used to transmit signals
- vary continuously in amplitude

- can have any value within a fixed range

48

What are digital signals?

- used to transmit data as a series of pulses.

- do not vary, they have two states, on (1) and off (0)

49

What us multiplexing?

- when two or more digital signals are sent down the same optical fibre at the same time.

- enables more information to be sent in one go.

50

What are the advantages and disadvantages of wireless communication?

Advantages:
> no connections to a phone land-line needed
> portable, convenient! allows access anywhere

Dissadvantages:
> aerial is needed to pick up signal

51

How are satellites used for global communication?

- a signal is sent from a ground station transmitter dish, to a satellite receiver dish.

- a return signal is then sent by the satellite transmitter to a ground receiver dish.

52

What is the Ionsphere?

- an electrically charged layer in the Earths upper atmosphere

- reflects longer wavelength radio waves

53

What does Refraction at the interfaces of different layers of the Earths atmosphere result in?

- Waves changing direction

- Diffraction at the edge of transmission dishes causes the waves to spread out, which results in signal loss

54

What are the advantages and disadvantages of DAB radio?

Advantages:
- more stations available
- less interference with other stations

Dissadvantages:
- audio quality is not as good as FM broadcasts
- not available everywhere

55

What are seismic waves?

- shock waves produced by earthquakes

56

What are the two types of Seismic waves?

P-waves (primary waves)
- longitudinal and travel through both solids and liquids

S-waves (secondary waves)
- are transverse waves and travel through solids but not liquids. Travel slower than P-waves

57

What will happen to a wave as it passes from one medium to another?

- it will speed up or slow down

58

What is Refraction?

-When a wave changes direction when it passes from one medium to another