Electrical and Electronic Fundamentals
What this domain tests
Electrical and Electronic Fundamentals covers basic circuit laws, components, measurements, and safe practice. You should be able to calculate current, voltage, resistance, and power, and recognise how series and parallel networks behave.
Core rules
- Ohm's law: V = IR. Power: P = VI = I²R = V²/R.
- Series: same current; resistances add; voltages divide in proportion to resistance.
- Parallel: same voltage; 1/Rtotal = 1/R1 + 1/R2 + ...; branch currents add.
- A diode conducts from anode to cathode when forward-biased; a capacitor blocks steady DC but passes changing signals.
- Measure voltage in parallel and current in series; never connect an ammeter across a supply.
- Prefixes: k = 10³, M = 10⁶, m = 10⁻³, µ = 10⁻⁶.
Worked example
A 12 V supply is connected across a series combination of 4 Ω and 6 Ω. Find the current and the voltage across each resistor. Total resistance = 4 + 6 = 10 Ω. Current I = V/R = 12/10 = 1.2 A. The 4 Ω resistor drops V = 1.2 × 4 = 4.8 V; the 6 Ω resistor drops 1.2 × 6 = 7.2 V. The drops add to 12 V, as required. Total power = 12 × 1.2 = 14.4 W.
Traps
- Adding resistances in parallel directly instead of using reciprocals.
- Assuming the same current flows through parallel branches.
- Using the wrong prefix, especially mA versus A.
- Measuring current with the meter set to volts.