Circuit symbols

• Science
• Lower Secondary (Key Stage 3)

You have 3 minutes to memorise these symbols.

Bulb/Lamp

Cell

Open Switch

Closed Switch

Fuse

Ammeter

Voltmeter

Resistor

Variable

Resistor

Describe the circuit

Will the bulb light up?

Describe the circuit

Will the bulb light up?

Describe the circuits

Will the bulbs light up?

Electric Circuits

• The simplest complete circuit is a piece of wire from one end of a battery to the other.
  
• An electric current can flow in the wire from one end of the battery to the other, but nothing useful happens.
  
• The wire just gets very hot and the battery loses stored internal energy – it ‘goes flat’ and stops working.
  

What type of current flows in one direction?

1. Pulsating current
2. Alternating current
3. Static current
4. Direct current

Current

• Current is a measure of how much electric charge flows through a circuit
  
• Current flows from positive to negative
  
• The more charge that flows, the bigger the current.
  
• Measured in Amperes (A) or amps
  
• Symbol = I
  

Charge

• Since electrons are very small
  
• One electron will not have much of an effect
  
• It is more useful to refer to packages of electrons
  
• One coulomb of charge is a package equivalent to 6,250,000,000,000,000,000 electrons
  

Electric Current

• To measure the current we use an Ammeter. 
  
• It simply 'counts' how many Coulombs pass by a point in the circuit every second. 
  
• The unit of Electric Current is called Ampere (A).

 

What is the unit of electrical current?

1. Ohm
2. Volt
3. A
4. Ampere

What is the symbol for current?

1. R
2. I
3. C
4. i

What device measures electrical current?

1. Ohmmeter
2. Ammeter
3. Current meter
4. Voltmeter

What is direct current's abbreviation?

1. Direct current
2. Alternating current
3. DC
4. AC

What does a resistor do in a circuit?

1. Amplifies signal
2. Stores energy
3. Limits current flow
4. Generates power

What is a closed circuit?

1. Path is broken
2. Path is complete
3. Path is faulty
4. Path is open

Match the keyword to the definition.

Flow of electrons through a wire.

Components arranged in a loop, joined by wires.

Push that makes charge move (provided by a battery/cell).

Current 

Potential difference

Circuit