Railway LDCE Assistant Signal & Telecom Engineer Practice Quiz

Question 1

A 24 V DC source feeds two equal 120 ohm resistors in series. What voltage appears from their junction to the negative rail?

Accepted Answer

12 V, because equal series resistors divide the source equally under Kirchhoff's voltage law

Question 2

A lagging AC load draws 8 kW real power and 10 kVA apparent power. What is its power factor, and what does the figure mean?

Accepted Answer

0.8 lagging; current lags voltage

Question 3

Three equal loads are star-connected to a balanced three-phase supply. How are line and phase quantities related?

Accepted Answer

Line voltage is root-three times phase voltage, while line current equals phase current

Question 4

A coil has 30 ohm resistance and 40 ohm inductive reactance at the supply frequency. What is the impedance magnitude, and how does current phase compare with voltage?

Accepted Answer

50 ohm; current lags voltage because net reactance is inductive

Railway LDCE Assistant Signal & Telecom Engineer — Syllabus & notes

Exam overview