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Physics > P4 > Flashcards

P4 Flashcards

1
Q

What two things compose the nucleus of an atom?

A

Protons and neutrons.

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2
Q

What charge does each component of an atom have?

Proton?
Neutron?
Electron?

A 
Proton= Positive charge 
Neutron= No charge
Electron= Negative Charge
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3
Q

An _________ atom has equal numbers of electrons and protons

A

Uncharged

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4
Q

What can only be transferred to or from an atom?

A

Electrons

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5
Q

What is a charged atom called?

A

An ion

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6
Q

What does adding electrons to an uncharged atom do? (explain why)

A

It makes it negative because the atom has more electrons than protons.

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7
Q

What does removing electrons to an uncharged atom do? (explain why)

A

It makes it positive because the atom has fewer electrons than protons.

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8
Q

Rubbing a polythene ___ with a dry _____transfers electrons to the surface atoms of the rod from the cloth. So the polyethene rod becomes __________charged.

A

rod
cloth
negatively

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9
Q

Rubbing a _______ rod with a dry cloth transfers _________ from the surface atoms of the rod on to the cloth. So the perspex rod becomes __________ charged. Its positive charge is _____ to the negative charge of the dry cloth.

A

perspex
electrons
positively
equal

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10
Q

Two charged objects exert a non-contact force on each other because of their charge. This is because a charged object creates an ________ _____ around itself.

A

electric field

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11
Q

What happens to a second charged object within the field as the distance between them decreases?

A

As the distance decreases, the force between the two charged objects becomes stronger.

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12
Q

What do the lines on an electric field represent?

A

Electric field lines reveal information about the direction (and the strength) of an electric field within a region of space.

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13
Q

In what way would the lines on an electric field point if the sphere were negatively charged?

A

The lines would point towards the centre of the sphere.

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14
Q

What would happen if the two objects were oppositely charged within the electric field?

A

Electrons in the air molecules between two objects experience a force towards the positive object. If the field is too strong, sparking happens because some electrons are pulled out of air molecules by the force of the field. These electrons hit other air molecules by the force of the field.

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15
Q

What would happen if the field is too strong between the two objects?

A

Sparking happens because some electrons are pulled out of air molecules by the force of the field. These electrons hit other air molecules by the force of the field.

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16
Q

Does the same type of charges attract or repel each other?

A

The charges will repel each other.

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17
Q

Does the same type of charges attract or repel each other?

A

The charges will attract each other.

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18
Q

What does a circuit diagram show you?

A

It shows you how the components in a circuit are connected together.

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19
Q

What is a cell necessary for in a circuit?

A

A cell is necessary to push electrons around a complete circuit.

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20
Q

How many cells does a battery have?

A

Two or more.

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21
Q

What does the plus sign near the battery signal?

A

This signals that it is the positive terminal of the cell.

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22
Q

What does the switch enable in the circuit?

A

It enables the current in a circuit to be switched on or off.

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23
Q

What does the bulb do in the circuit?

A

It is designed to emit light as a signal when a current passes through it.

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24
Q

What does a diode do?

A

A diode allows current through in one direction only.

25
Q

What does LED stand for and what does it do?

A

LED stands for a light-emitting diode. It emits light when current passes through it.

26
Q

How is an ammeter used?

A

An ammeter is used to measure electric current.

27
Q

What does a fixed resistor do?

A

It limits the current in a circuit.

28
Q

What does a variable resistor do?

A

It allows the current to be varied.

29
Q

What does a fuse do?

A

A fuse is designed to melt and therefore ‘break the circuit if the current through it is greater than a certain amount. This is a great safety feature and used in most electrical appliances.

30
Q

What does a heater do in a circuit?

A

A heater is designed to transfer the energy from an electric current to heat the surroundings.

31
Q

What does a voltmeter do in a circuit?

A

A voltmeter is used to measure the potential difference (voltage).

32
Q

What is an electric current?

A

It is a flow of charge.

33
Q

The size of an electric current is the ____ of the flow of electric charge.

A

rate

34
Q

The bigger the number of electrons that pass through a _________ each second, the bigger is the _______ passing through it.

A

component

current

35
Q

What is the rule of current in a single closed-loop circuit?

A

The current at any point in the circuit is the same as the current at any other point in the circuit.

36
Q

What is electric charge measured in?

A

It is measured in coulombs (C).

37
Q

What is electric current measured in?

A

It is measured in amperes (A)- more commonly known as amps.

38
Q

What is the equation that relates charge flow, current, and time taken (give units)?

A

Charge flow, q (Coulombs)=current, I (Amperes)* time taken, t (seconds)

39
Q

Why is an ammeter used and what can it show?

A

An ammeter is connected in a series with the bulb, so the current through them is the same. The ammeter tells you the current in amperes.

40
Q

What is milliampere the unit for?

A

Small currents. (1mA=0.001 A)

41
Q

What is voltage?

A

It is the energy transferred to the bulb or the work done on it by each coulomb of charge that passes through it. The unit is volts (V).

42
Q

Where is the voltmeter connected in the circuit?

A

The voltmeter is connected in parallel with the torch bulb. so it measures the potential difference across it. The voltmeter tells you the potential difference in volts.

43
Q

What is the equation that links: potential difference, energy transferred, and charge.

A

Potential difference across a component (Volts, V)= Energy transferred (Joules, J) / Charge (Coulombs, C)

44
Q

What does a resistor do in a circuit?

A

A resistor in a circuit limits the current that flows around the circuit.

45
Q

In what proportion are resistance and current?

A

Inversely proportional.

The larger the resistance, the smaller the current.

46
Q

What is the equation to find resistance?

A

Resistance (ohms, Ω)= potential difference (Volts, V) / Current (amperes, A)

47
Q

In what proportion are potential difference and current?

A

They are in direct proportion. As the potential difference increases, so does the current.

48
Q

What is Ohm’s law?

A

The current through a resistor at constant temperature is directly proportional to the potential difference across the resistor.

49
Q

What is an ohmic conductor?

A

It is a wire because its resistance stays constant as the current changes as long as the temperature is constant.

50
Q

The resistance is the ____ no matter what direction the current is in.

A

same

51
Q

What are the three rules for components in a series circuit?

A

The current is the same in each component.

The total potential difference is shared between the components.

Adding their resistance gives you the total resistance as it is shared.

52
Q

For cells in ______, acting in the same direction, the _____ potential difference is the ___ of their individual potential differences.

A

series
total
sum

53
Q

What is the equation for total resistance in a series circuit?

A

R(total)= R1+R2.

54
Q

What does adding more resistors in a series circuit do and why?

A

It increases the total resistance because the current through the resistors is reduced and the total potential difference across them is unchanged.

55
Q

What are the two rules for components in a parallel circuit?

A

The total current is the sum of the currents through separate components.

The potential difference across each component is the same.

56
Q

The bigger the __________ of a component, the smaller the _______ that will pass through that component.

A

resistance

current

57
Q

What is the equation to find the current through a resistor in a parallel circuit?

A

Current= Voltage / Resistance

58
Q

What does adding more resistors in a parallel circuit do and why?

A

It will decrease the total resistance because the total current through the resistors is increased and the total potential difference across them is unchanged.

Physics (6 decks)

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