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GCSE Physics > Topic 10 > Flashcards

Topic 10 Flashcards

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1
Q

What is current ?

A

Electrical current is the flow (movement) of electric charges

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2
Q

What is electrical current measured in ?

A

Electric current is measured in amperes (A). Current has the same value at any point in a single closed loop

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3
Q

How do you calculate the flow of charge ?

A

The flow of charge (C) = current (A) x time (s).

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4
Q

In a closed loop if the current is 10(A) in one point what is it at another point?

A

10(A)

Because A current has the same value at every point in a single closed loop.

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5
Q

I = Q/t

A

Current (C) = charge(A) / time (s)

Coulombs Amps Seconds

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6
Q

current = charge / time

How would you rearrange this equation if you wanted to calculate charge ?

A

Charge = current x time

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7
Q

What are the units for current?

A

Amperes

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8
Q

What is an electrical conductor ?

A

An electrical conductor is material that allows electric currents (flow of electric charges) to pass through it.

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9
Q

What are all electrical conductors made from ?

A

All metals are electrical conductors

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10
Q

What are electrical insulators ?

A

An electrical insulator is a material that doesn’t allow electric currents (flow of electric charges) to pass through it.

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11
Q

What are two electrical insulators ?

A

Plastic and glass are electrical insulators

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12
Q

What allow electrical conductors too conduct electricity?

A

The free electrons inside electrical conductors explain why they can conduct electricity

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13
Q

What makes an electrical insulator ?

A

An electrical insulator has no free electrons.

No charges are free to move and carry a current.

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14
Q

What makes an electrical conductor ?

A

An electrical conductor has lots of charges that are free to move.

In a metal, the charges that are free to move are electrons.

The electric current through the metal is the flow of these free electrons

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15
Q

What is potential difference ?

A

Potential difference is the difference in the amount of energy that charge carriers have between two points in a circuit.

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16
Q

How can potential difference be described ?

A

It can be described as the energy transferred by unit charge passed

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17
Q

What is potential difference measured in ?

A 
Potential difference (p.d.) is measured in volts (V) and is also called voltage.
The energy is transferred to the electrical components in a circuit when the charge carriers pass through them.
18
Q

What do we use to measure potential difference ?

A

We use a voltmeter to measure potential difference (or voltage).

19
Q

V =?

A

E / Q

20
Q

Voltage x charge = ?

A

Voltage x charge = energy

21
Q

What do ammeters measure ?

A

An ammeter measures the flow of current that passes through a wire

22
Q

How do ammeters have to be connected ?

A

Ammeters have to be connected in series (in the same loop of the circuit) with the electrical component whose current you are measuring.

23
Q

What do voltmeters measure ?

A

Voltmeters measure potential difference (voltage) between two points in a circuit.

For example between two points either side of a component.

24
Q

How do voltmeters have to be connected ?

A

Voltmeters must always be connected in parallel (on a separate branch of the circuit) with the two points being measured.

25
Q

What’s the difference between current and potential difference ?

A

The current is a flow of charge. Current is measured through a component.

Potential difference is the energy used between two points in a circuit, therefore it is measured between two points either side of a component.

We describe this as the potential difference measured across a component.

26
Q

If voltage is 5V and charge is 3C, what is the energy transferred?

A

Voltage = energy / charge
Energy = voltage x charge
5V x 3C = 15J

27
Q

Fact

A

A potential difference of one Volt is equal to one Joule of energy being used by one Coulomb of charge when it flows between two points in a circuit

28
Q

What is resistance a measure of ?

A

Resistance is a measure of how difficult it is for current to flow through a component

29
Q

How is resistance measured ?

A

Resistance is measured in ohms, Ω.

30
Q

When charge flow is in an electrical current the size of the current is affected by what two things?

A

The resistance: If the resistance is increased, the current will decrease.

The potential difference: If the potential difference is increased the current will increase.

31
Q

What is ohm’s law ?

A

The resistance between two points in a circuit is equal to the potential difference between those two points, divided by the current flowing through them.

32
Q

What’s the symbol and word equation for ohms law ?

A 
R = V/I
Resistance = potential difference/current
33
Q

How would Ohm’s Law be rearranged to calculate potential difference .

A

Potential difference = current x resistance

34
Q

What instruments do we use to calculate resistance ?

A

We calculate potential difference using a voltmeter and current using an ammeter at the same time

35
Q

When a wire is longer what does this do to the resistance?

A

The longer the wire, the higher the resistance

36
Q

What do we use to measure a current flowing through a component ?

A

Ammeter

37
Q

To measure the resistance of a component (e.g. lamp or resistor) what should we do ?

A

measure the potential difference across the component.

38
Q

What is An Ohmic conductor ?

A

a conductor that obeys Ohm’s Law.

39
Q

If The current through an ohmic conductor (at a constant temperature) is directly proportional to the potential difference across the resistor. What does this mean for the resistance?

A

This means that the resistance remains constant as the current changes.

40
Q

To measure resistance what do you need ?

A

A voltmeter in parallel
An ammeter in series
Ohms law

GCSE Physics (11 decks)

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