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Physics · Grades 7–10

Charge, current and complete circuits

Describe a steady circuit without saying that current is consumed.

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Learn the idea

Charge

Charge is a conserved property measured in coulombs; its movement constitutes electric current.

Current

Current is charge transfer per second. In a steady single-loop circuit the current is the same around the loop.

Energy

Components can transfer electrical energy while charge continues around the circuit. Current is not used up by the first lamp.

Safety

These are paper models. No mains wiring, high-current experiment or construction instruction is required.

Worked examples

A current of 2 A flows for 6 s. Find charge transferred.

Q = It = 2 × 6 = 12 C.

12 C

A charge of 15 C passes in 5 s. Find current.

I = Q/t = 15/5 = 3 A.

3 A

Check your understanding

  1. In a steady series circuit, current after a resistor is generally what compared with current before it?

    1. The same
    2. Always half
    3. Always zero

  2. What does a lamp primarily transfer from the electrical system?

    1. All of the circuit's charge permanently
    2. Energy
    3. The time coordinate

  3. Why is current is used up in a resistor misleading?

Answers and marking notes

Answers and marking notes
  1. The same

    Charge is not accumulating at the resistor in the steady model.

  2. Energy

    Energy transfers while the same rate of charge flow continues in steady state.

  3. A resistor transfers energy, but steady charge flow does not decrease along a series path.

    Credit energy-versus-charge distinction.

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.