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Flashcards in Unit 3 Deck (71):
1

What is resistance?

How much of a component opposes the flow of current

2

As total resistance increases what happens to the current?

It decreases

3

What is resistance measured in?

Ohms

4

What kind of charge does an electron have?

Negative

5

What kind of charge does a proton have?

Positive

6

What do objects with the same charge do when placed close together?

Repel each other

7

What do objects with opposite charge do when paced close together?

Attract each other

8

Are electrons free to move in a conductor?

Yes

9

Are electrons free to move in insulators?

No

10

What happens when two insulators a rubbed together?

Become electrically charged - transfer electrons between them though friction

11

How are the comments linked in a series circuit?

In a loop

12

How would make an object positively/ negatively charged?

Electrons must be added/ removed

13

What is current?

The amount of charge flowing per second

14

What is current measured in?

Amperes (A)

15

What is one amp equal to?

One columb per second

16

What is an electric field?

The region around an electric charge

17

What do electrical field lines indicate?

The force exerted on a positive electric charge. Lines closer together - greater force exerted

18

What is voltage?

A measure of the energy given to the charges in a circuit

19

What is voltage measured in?

Volts (V)

20

What is potential difference?

Measure of the difference in energy across two points in a circuit

21

What does one volt equal?

One joule per coulomb

22

What is a voltage divider circuit?

Uses two or more resistors in series to provide a part of a supply voltage

23

Why are voltage divider circuits used?

To prevent a component getting damaged

24

In a voltage divider circuit is the current equal at all points?

Yes

25

When temperature is increased on a thermistor, what happens to the resistance?

It decreases

26

When light increases in a LDR, what happens to the resistance?

Decreases

27

What does a diode allow the current to do in a circuit?

Flow in one direction

28

What can a diode do to the power in a circuit?

Change it from AC to DC

29

What is a transistor?

A voltage controlled switch, responds to a change at the input

30

What are the two types of transistors?

Bi-polar transistor and MOSFET

31

What are capacitors?

Components that store charge and energy

32

What happens when a capacitor is connected to a power supply?

Capacitor charges and a potential difference is created across the capacitor

33

When resistance increases, what happens to the time taken for capacitor to charge?

Greater time to charge

34

Capacitors can be used in what type of circuits?

In timing circuits, eg-alarms

35

What is power?

How much energy is transferred per second

36

What is power measured in?

Watts (W)

37

How is power loss in transmission lines calculated?

P=I^2R

38

What does a step up transformer in power lines do?

Increases voltage across transmission lines

39

Wha does a step down transformer do in transmission lines?

Reduces voltage to a safe level

40

How is power loss reduced in transmission lines?

Voltage is increased meaning current decreases

41

What is a fuse?

A wire with a low melting point

42

If the current in a circuit is too high what happens to the fuse?

Heats up and melts

43

What is a ring circuit used for?

Used to connect a set of main sockets

44

What are some advantages of ring circuits?

Lower current in wires, thinner wires (less current), low cost, mains sockets can be easily added/removed

45

What is energy measured in?

Joules (J)

46

What is gravitational potential energy?

A object gains this energy when it is raised

47

What is kinetic energy?

An object gains this energy when it's moving

48

Can energy be created or destroyed?

No energy is lost or transformed from one type to another

49

When a ball is dropped what kind of energy has it got?

Potential energy hen when dropped it is transformed into kinetic energy

50

During every energy transfer some energy is lost to the surroundings as what?

Heat energy

51

What does lost energy equal?

Initial energy - final energy

52

What is the efficiency of a device?

How much of the energy input is transformed into useful energy output

53

What is temperature?

A measure of how hot or cold an object is

54

To find the temperature in kelvin what do you do?

Tc + 273

55

When a substance is heated what happens to the atoms?

Atoms vibrate faster and kinetic energy of atoms increases

56

What is conduction?

Thermal energy is transferred by vibrating atoms

57

What is convection?

Thermal energy is transferred by movement of atoms within a substance (only happens in liquids and gases)

58

What is radiation?

Thermal energy is radiated as electromagnetic waves

59

What is specific heat capacity?

The amount of heat energy required to change the temperature of 1 kg of a substance by 1 degree

60

What is pressure?

The force per unit area

61

What is pressure measured in?

Pascals (Pa)

62

What is an example of high pressure?

Sharp knife through food

63

What is an example of low pressure?

Snow boots

64

In a kinetic model of gas does each particle have different values of kinetic energy?

Yes, they move at different velocities

65

What is Boyle's Law?

Pressure is inversely proportional to a fixed mass of gas at a constant temperature

66

What is the equation for Boyle's Law?

p1V1 = p2V2

67

What is the Pressure Law?

For a fixed mass of gas at a constant volume , pressure is directly proportional to temperature

68

What is the equation for Pressure Law?

p1/T1 = p2/T2

69

What is Charles' Law?

As temperature increases, volume increases. For a fixed mass of gas at a constant pressure

70

What is the equation for Charles' Law?

V1/T1 = V2/T2

71

What is the general gas equation?

p1V1/T1 = p2V2/T2