Current — Science definition
Defined in 2 courses:
- The rate of electric-charge flow through a chosen part of a circuit, measured in amperes (A). (Physical Science: Matter, Forces & Energy)
- The flow of electric charge, measured in amps (A). (Physical Science: Matter, Forces & Energy)
Where it is taught
- Electric & Magnetic Forces — Forces, Physical Science: Matter, Forces & Energy, Grade 8
- Electricity & Simple Circuits — Energy & Heat Transfer, Physical Science: Matter, Forces & Energy, Grade 8
In use
A simple direct-current circuit provides a complete conducting path through a source and components.
Electricity & Simple Circuits
Questions using current
Problem 1
Explain how changing current can make a speaker produce sound. Name the coil, fixed magnet, cone and surrounding air.
Answer and explanation
Changing coil current changes the magnetic interaction and force on the coil. The attached cone vibrates and disturbs air, producing sound waves.
Follow the supplied cutaway connections.
Explain a mechanism between each pair of parts.
Response criteria
- Connect current to magnetic force.
- Connect coil to cone motion.
- Connect repeated cone motion to air vibration.
Problem 2
A circuit has 9 volts and 3 ohms of resistance. Find the current.
Answer and explanation
3 A
I = V ÷ R = 9 ÷ 3 = 3 A.
Problem 3
A current of 4 amps flows through a 6-ohm resistor. Find the voltage.
Answer and explanation
24 V
V = IR = 4 × 6 = 24 V.
Problem 4
A 15-volt circuit has a current of 5 amps. Find the resistance.
Answer and explanation
3 Ω
R = V ÷ I = 15 ÷ 5 = 3 Ω.
Taught alongside
- field
- repel
- controlled variable
- model
- evidence
- system boundary
- assumption
- electric charge
- polarization
- coil
- electromagnet
- compass
- circuit
- voltage