Physics Topic
Electric Charge, Current, and Circuits
- Read notes
- Flashcards
- Quiz
- Confident
Study focus - 3 things
- Electric current is the flow of electric charge
- The formula is current = charge / time
- A simple circuit needs a complete path, a power source, and components
Section 1Electric charge
Electric charge is a property of particles that causes electrical effects. Charge is measured in coulombs, written C. In school circuits, the moving charges are usually electrons in wires.
Section 2Electric current
Current is the rate of flow of charge. The formula is current = charge / time, or I = Q / t. Current is measured in amperes, written A.
Section 3Simple circuits
A simple circuit is a complete path for current to flow. It usually includes a cell or battery, wires, and a component such as a bulb or resistor. Watch out: if the circuit is broken, current cannot flow.
Section 4Real-life anchor
When JPS power goes out, appliances stop because the circuit supplying energy is no longer working as normal. In a small classroom circuit, the same basic idea applies: no complete path, no current through the component.
Examples
A charge of 20 C flows past a point in 5 s. Find the current.
Current = charge / time = 20 / 5 = 4 A.
A small fan at home stops when a wire in its circuit breaks. Why?
The circuit is no longer complete, so charge cannot flow around the path and the fan gets no current.
Now let's water it
Session runs notes to flashcards to quiz back-to-back.