Electronics Information: Circuits and Components
Electronics Information tests basic electrical concepts: current, voltage, resistance, circuits, and common components. Understanding a few relationships covers most questions.
Core concepts
- Voltage (V) is electrical pressure; current (I) is flow rate, in amperes; resistance (R) opposes flow, in ohms.
- Ohm's Law: V = I × R. Rearrange as needed: I = V/R, R = V/I.
- Power: P = V × I (watts).
- Series circuits: one path; current is the same everywhere; resistances add (R_total = R₁ + R₂ + …); voltage divides.
- Parallel circuits: multiple paths; voltage is the same across branches; current divides; total resistance is less than the smallest branch.
- Components: resistors limit current; capacitors store charge; diodes allow current in one direction; LEDs emit light; switches open/close circuits; batteries supply DC voltage.
Traps
- Mixing series and parallel rules-know which quantity stays constant.
- Unit confusion: amps vs. volts vs. ohms vs. watts.
- Assuming a broken path still conducts-an open circuit stops current.
- Ignoring that adding parallel branches lowers total resistance.
Worked example
A 12-volt battery is connected to a 4-ohm resistor. What current flows? Using I = V/R: I = 12 V ÷ 4 Ω = 3 A. Power dissipated = V × I = 12 × 3 = 36 W. The estimate confirms a reasonable current for a low-resistance load.
Rule of thumb
Write down what you know (V, I, R, P) and use Ohm's Law or the power formula to find the missing value.