HAM HAM Radio Extra Class Test Advanced Electrical Principles Questions and Answers 2

Question 1

What is the skin effect in RF conductors?

Accepted Answer

Current flows only on the surface of the conductor at high frequencies

Answer

Skin effect causes RF current to concentrate near the outer surface of a conductor, increasing effective resistance at higher frequencies.

Question 2

In a series RLC circuit at resonance, what is the impedance equal to?

Accepted Answer

The resistance only

Answer

At resonance the inductive and capacitive reactances cancel, leaving only the resistance as the total impedance.

Question 3

What is the quality factor (Q) of a parallel resonant circuit with R = 10 kohms, L = 10 uH, and C = 10 pF?

Accepted Answer

100

Answer

For a parallel RLC circuit, Q = R / (2 * pi * f * L), and at resonance with these values Q equals approximately 100.

Question 4

What happens to the time constant of an RC circuit if the capacitance is doubled?

Accepted Answer

The time constant doubles

Answer

The time constant tau equals R times C, so doubling the capacitance directly doubles the time constant.

Question 5

What is the phase angle between voltage and current in a purely inductive circuit?

Accepted Answer

Voltage leads current by 90 degrees

Answer

In a purely inductive circuit, voltage leads current by exactly 90 degrees due to the inductor opposing changes in current.

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