Circuit symbols are used to represent components in circuit diagrams.
Understanding and using circuit symbols is important for drawing and interpreting circuit diagrams.
The electromotive force (e.m.f.) of a source is the energy transferred per unit charge when driving charge around a complete circuit.
Differentiate between e.m.f. and potential difference (p.d.) based on energy considerations.
The internal resistance of a source of e.m.f. affects the terminal potential difference in a circuit.
10.2 Kirchhoff's laws:
Kirchhoff's first law states that the total current entering a junction in a circuit is equal to the total current leaving the junction, based on the principle of conservation of charge.
Kirchhoff's second law (loop rule) states that the sum of the e.m.f.s and potential differences in any closed loop of a circuit is equal to zero, based on the principle of conservation of energy.
Using Kirchhoff's laws, formulas for the combined resistance of resistors in series and parallel can be derived.
The combined resistance of resistors in series is found by adding the individual resistances.
The combined resistance of resistors in parallel is found using the formula 1/R = 1/R1 + 1/R2 + 1/R3 + ... (for two or more resistors).
Kirchhoff's laws can be used to solve simple circuit problems.
10.3 Potential dividers:
A potential divider circuit is a circuit that divides a voltage into smaller fractions using resistors.
The principle of a potentiometer can be used to compare potential differences.
A galvanometer is used in null methods to balance a circuit and measure unknown potential differences.
Thermistors and light-dependent resistors (LDRs) can be used in potential dividers to provide a potential difference that depends on temperature and light intensity, respectively.