Electrical Engineering questions for GATE, PSU recruitment and SSC JE draw from network theory, electrical machines, power systems, control systems, measurements and instrumentation, analog and digital electronics, and electromagnetic fields. Numerical answers include the formula used and the unit at each stage, which is where marks are commonly lost even when the approach is correct.
In a three-phase power measurement using two-wattmeter method, the power factor can be determined from which relationship?
Answer: A
For two-wattmeter method in three-phase systems: tan(φ) = √3(W₁ - W₂)/(W₁ + W₂), used to calculate power factor.
Q.527Medium
A standard cell has an EMF of 1.0186 V at 20°C with temperature coefficient of -0.0004 V/°C. What will be its EMF at 25°C?
Answer: B
EMF at 25°C = 1.0186 - 0.0004 × (25-20) = 1.0186 - 0.002 = 1.0166 ≈ 1.0170 V.
Q.528Easy
Which bridge circuit is specifically designed to measure inductance with small resistance?
Answer: A
Maxwell bridge is used for measuring inductance (especially with small resistance) in industrial and laboratory applications.
Q.529Medium
In a LVDT (Linear Variable Differential Transformer), when the core is at null position, what happens to the output voltage?
Answer: B
At null position in LVDT, the core is centered, and secondary voltages from both coils cancel out, resulting in zero or minimum output.
Q.530Easy
A pressure transducer has sensitivity of 0.5 V/bar. If input pressure varies from 0-10 bar, what is the output voltage range?
Answer: B
Output voltage = Sensitivity × Pressure = 0.5 × 10 = 5 V for maximum pressure of 10 bar.
Q.531Medium
In a potentiometer method for EMF comparison, if standard cell EMF is 1.018 V with 106.4 cm length, and unknown cell requires 107.8 cm, what is unknown EMF?
A light intensity meter using a photocell shows reading of 500 lux. If the luminous intensity of the source is constant, what happens to the reading when distance is doubled?
Answer: B
Illuminance follows inverse square law: E ∝ 1/d²; when distance doubles, illuminance becomes 41th: 4500 = 125 lux.
Q.535Easy
Which of the following logic gates produces output 1 only when all inputs are 1?
Answer: A
AND gate produces 1 only when all inputs are 1. For 2-input AND: output = A.B
Q.536Easy
What is the Boolean expression for XOR gate with inputs A and B?
Answer: B
XOR produces 1 when inputs are different: A⊕B = A.B' + A'.B
Q.537Easy
How many flip-flops are required to design a MOD-16 counter?
