NSQF Vocational Trade Theory (Electronics)
What the theory paper tests
The NSQF Vocational Trade Theory (Electronics) domain checks whether you can explain, not just recognise, the trade. Expect questions on electrical quantities and units, component symbols and colour codes, Ohm’s law, series and parallel networks, AC/DC differences, semiconductors, rectifiers, transistors, digital gates, power supplies, and safe measurement practice. PSEB matric NSQF papers often link each fact to a shop-floor task, so learn the reason behind a rule.
Core rules to hold
- Current is measured in amperes (A), voltage in volts (V), resistance in ohms (Ω); 1 kΩ = 1000 Ω and 1 mA = 0.001 A.
- Ohm’s law: V = IR. In a series circuit, current is common and voltages add; in parallel, voltage is common and currents add.
- Resistor colour code: first two bands are digits, third is multiplier, fourth is tolerance. Gold = ±5%, silver = ±10%, none = ±20%.
- A diode conducts from anode to cathode when forward biased; a transistor has emitter, base and collector, with base controlling current.
- AC is specified as RMS unless stated; peak = RMS × 1.414 for a sine wave.
Worked example
A resistor is banded brown, black, red, gold. Brown = 1, black = 0, red multiplier = ×100, so 10 × 100 = 1000 Ω = 1 kΩ. Gold gives ±5%, i.e. 950 Ω to 1050 Ω. Across a 9 V supply, I = V/R = 9/1000 = 0.009 A = 9 mA. If you wrote 9 A, you forgot to convert 1 kΩ to 1000 Ω.
Traps that cost marks
Reading the tolerance band as the multiplier; mixing series and parallel rules; ignoring unit prefixes; assuming a diode is a resistor; and quoting peak voltage when the question asks for RMS.