Overview
This lecture introduces the basics of series circuits and electric current, including circuit symbols, current flow, and measurement.
Circuit Symbols and Components
- Scientists use standard symbols to represent circuit components: cell, lamp, open switch, and closed switch.
- Components are connected with lines representing wires.
Electric Current in a Circuit
- Electric current is the flow of electrons from the negative end to the positive end of a cell.
- Electrons carry energy from the cell, transferring it to components like lamps (converted to light and heat).
- Electrons have less energy after passing through components and returning to the cell.
Conventional Current Direction
- Conventionally, current is shown flowing from positive to negative, even though electrons flow in the opposite direction.
- This convention is called "conventional current" and is used in circuit diagrams.
Series Circuits
- A series circuit has no branches; current flows in one continuous path.
- The electric current is defined as the flow of electrical charge around the circuit.
Measuring Electric Current
- The unit for current is the ampere (A), often called "amp."
- Current is measured using an ammeter, represented by a specific symbol.
- In a series circuit, the current is the same at every point and is not used up.
Key Terms & Definitions
- Component — a part of a circuit, such as a cell, lamp, or switch.
- Electric current — the flow of electrons (charge) around a circuit.
- Series circuit — a circuit with no branches; current has a single path.
- Ampere (A) — the unit for measuring electric current.
- Ammeter — a device that measures electric current.
- Conventional current — the direction from positive to negative used in diagrams, opposite to actual electron flow.
Action Items / Next Steps
- Learn the circuit symbols for cell, lamp, open switch, closed switch, and ammeter.
- Practice describing current flow and measuring current in series circuits.