GCSE Physics: Electricity Flashcards

Question 1

Define Electric Current.

Accepted Answer

The rate of flow of electric charge around a circuit, measured in amperes (A). In metal wires the moving charges are electrons.

Question 2

Define Charge Flow Equation.

Accepted Answer

Q = It: charge flow in coulombs equals current in amperes multiplied by time in seconds. It links how much charge moves to how long it flows.

Question 3

Define Potential Difference.

Accepted Answer

The energy transferred per unit of charge passing between two points in a circuit, measured in volts (V). One volt is one joule per coulomb.

Question 4

What is Resistance?

Accepted Answer

How strongly a component opposes the flow of current, measured in ohms. For a given potential difference, a higher resistance means a smaller current.

Question 5

Define V = IR.

Accepted Answer

Potential difference in volts equals current in amperes multiplied by resistance in ohms. Rearranged, it finds any one of the three from the other two.

Question 6

Define Ohmic Conductor.

Accepted Answer

A conductor whose current is directly proportional to the potential difference across it, as long as its temperature stays constant, so its resistance is fixed.

Question 7

Define I-V Characteristic.

Accepted Answer

A graph of current against potential difference for a component, showing how its resistance behaves as the potential difference is varied, including in reverse.

Question 8

Define Filament Lamp.

Accepted Answer

A lamp whose thin metal filament glows when hot. Its resistance increases as its temperature rises, so it is not an ohmic conductor.

Question 9

What is Diode?

Accepted Answer

A component that allows current to flow through it in one direction only, because it has a very high resistance in the reverse direction.

Question 10

Define Light-Emitting Diode (LED).

Accepted Answer

A diode that gives out light when current flows through it in the forward direction. It uses much less energy than a filament lamp for the same light.

Question 11

Define Light-Dependent Resistor (LDR).

Accepted Answer

A resistor whose resistance falls as light intensity increases, being high in the dark and low in bright light.

Question 12

What is Thermistor?

Accepted Answer

A temperature-dependent resistor. In the GCSE type, its resistance decreases as its temperature increases, making it useful as a temperature sensor.

Question 13

Define Series Circuit.

Accepted Answer

A circuit with only one loop, so components are connected end to end. The current is the same everywhere and the supply potential difference is shared.

Question 14

Define Parallel Circuit.

Accepted Answer

A circuit with two or more branches. Each branch has the same potential difference as the supply, and branch currents add up to the total current.

Question 15

Define Resistors in Series.

Accepted Answer

When resistors are connected one after another, the total resistance is the sum of the individual resistances: R total = R1 + R2.

Question 16

Define Resistors in Parallel.

Accepted Answer

Connecting resistors side by side gives the current more paths, so the total resistance is lower than the resistance of the smallest individual resistor.

Question 17

What is Ammeter?

Accepted Answer

A meter that measures the current through a component, in amperes. It is always connected in series with that component so the same current passes through it.

Question 18

What is Voltmeter?

Accepted Answer

A meter that measures the potential difference across a component, in volts. It is always connected in parallel, across the component being measured.

Question 19

Define Electrical Power.

Accepted Answer

The rate at which energy is transferred by an appliance, measured in watts (W). It can be found with P = VI or with P = I squared R.

Question 20

Define Energy Transferred.

Accepted Answer

The energy an appliance transfers depends on its power and how long it runs (E = Pt), or on the charge that flows and the potential difference (E = QV).

Question 21

Define Direct Current (dc).

Accepted Answer

A current that always flows in the same direction, produced by a potential difference that does not change direction, such as from cells and batteries.

Question 22

Define Alternating Current (ac).

Accepted Answer

A current that repeatedly reverses its direction, produced by a potential difference that keeps switching between positive and negative.

Question 23

Define UK Mains Supply.

Accepted Answer

The electricity supplied to UK homes: an alternating current with a frequency of 50 hertz and a potential difference of about 230 volts.

Question 24

Define Live Wire.

Accepted Answer

The brown wire in a three-core cable, which carries the alternating potential difference from the supply at about 230 V relative to earth.

Question 25

Define Neutral Wire.

Accepted Answer

The blue wire in a three-core cable, which completes the circuit back to the supply and is at or close to 0 volts.

Question 26

Define Earth Wire.

Accepted Answer

The green and yellow striped safety wire, at 0 volts, connected to an appliance's metal case. It only carries current if there is a fault.

Question 27

What is Fuse?

Accepted Answer

A thin wire inside a plug that melts and breaks the circuit if the current gets too large, protecting the appliance and its cable.

Question 28

Define National Grid.

Accepted Answer

The nationwide system of cables and transformers that connects power stations to consumers, transmitting electricity at very high potential differences.

Question 29

Define Step-Up Transformer.

Accepted Answer

A transformer used at power stations that increases the potential difference, and so reduces the current, before electricity is sent through transmission cables.

Question 30

Define Step-Down Transformer.

Accepted Answer

A transformer that decreases the potential difference from the transmission cables to a much lower, safer level for homes and businesses.

Question 31

Define Static Electricity.

Accepted Answer

A build-up of charge on an insulator, caused when rubbing two insulating materials together transfers electrons from one surface to the other.

Question 32

Define Electric Field.

Accepted Answer

The region around a charged object in which another charged object feels a force. The field is strongest closest to the charged object.