Advanced Qualification · A-001 Advanced theory · A-001-002-005
Why is the resistance of a conductor different for RF currents than for direct currents?
- ABecause the insulation conducts current at high frequencies
- BBecause of skin effect
- CBecause of the Hertzberg effect
- DBecause conductors are non-linear devices
Correct answer: B — Because of skin effect. From the official ISED question bank, verified word for word.
Why
At radio frequencies, electric current tends to flow mostly along the outer surface of a conductor rather than through its entire cross-section, a phenomenon known as skin effect. The full explanation — and one for every question — is in Pro.
Practise this section
Advanced theory is section A-001 of the Advanced exam: Advanced theory: time constants, reactance, impedance, resonance, Q, and the mathematics behind tuned circuits.
Drill A-001 — free, no account