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The unit of current is Amperes.

# Electricity - Electrical Circuits 01

Electricity is an important topic in GCSE Physics. In this quiz we look at how the flow of electricity (the current) is measured in electrical circuits.

Electrical current flows in a closed path known as an electrical circuit. When a circuit is 'broken' it means that there is a gap which is stopping current from flowing. The break could be caused by a damaged component or wire, a component or connection that has become disconnected, or where there is a switch. Understanding the basic principles associated with electrical circuits is useful as it allows you to predict how circuits behave. If you learn a few simple equations, you will be able work out a wide variety of important values relating to circuits and components. By now, you should be very familiar with Ohm's law (V = I R) and have had plenty of opportunity to use it, but there are some other vital relationships related to electrical current and electrical circuits that you should know for your GCSE.

1.
What is electrical current?
Flow of electric charge
Flow of protons
Flow of neutrons
Flow of water
Current is the flow of electric charge around a circuit. The charge is carried by electrons which are emitted by the negative electrode of the cell and travel to the positive electrode of the cell through the circuit
2.
What is potential difference?
Work done per coulomb of charge that passes between two points
Kinetic energy per coulomb of charge that passes between two points
Work done per coulomb of charge that passes between three points
Work done per ampere of current that passes between two points
Strictly speaking, it should really be called electrical potential difference but at GCSE, potential difference is acceptable, when used in the correct context
3.
What is the work done in a circuit if the voltage is 10 V, the current is 4 A and the circuit is on for 25 seconds?
200J
500J
800J
1000J
You need to rearrange the equation V = WQ and work out the charge. Remember that one coulomb is one amp flowing for one second so if you have four amps flowing for 25 seconds, how many coulombs is that?
4.
Which formula calculates the size of the current?
I = Q x t
I = Qt
I = tQ
Q = It
If you didn't remember the equation, you can work it out. Whenever you need to calculate the rate of something in physics, it is expressed as something per second. To get the 'per second' bit, you know that you need to divide by time. That eliminates two of the alternative answers so the one that works out the current must be the correct one
5.
What does the size of the electric current depend on?
The rate of flow of electric charge
The rate of flow of protons
The rate of flow of neutrons
All of the above
High currents = bigger flow rates
6.
What is the formula for potential difference?
V = WQ
V = W2Q
V = 3W2Q
V = 5W3Q
V is in volts when W is in joules and Q is in coulombs
7.
What is the size of the current in a circuit if the charge, Q, is 100 C and lasts for 25 seconds?
1A
2A
3A
4A
Remember the definition - current is a measure of how much charge flows past a given point in one second. This should help you to get the right answer even if you can't recall the equation
8.
What is the unit of current?
Volts
Ohms
Amperes
Joules
Amperes or Amps for short is the unit of current. It is usually denoted with an A after a value of current
9.
What can be calculated from current-potential difference graphs?
Resistivity
Magnetism
Resistance
None of the above