GATE Technical: EE questions with solutions

Q1. The pressure coil of a dynamometer type wattmeter is

1. highly inductive
2. highly resistive
3. purely resistive
4. purely inductive

Answer: highly resistive

The pressure coil of a dynamometer type wattmeter is designed to measure voltage and is highly resistive to minimize the current drawn from the circuit, ensuring accurate voltage readings without significantly affecting the circuit's operation.

Q2. The measurement system shown in the figure uses three sub-systems in cascade whose gains are specified as G1, G2 and 1/G3. The relative small errors associated with each respective subsystem G1, G2 and G3 are ε1, ε2 and ε3. The error associated with the output is:

1. ε1 + ε2 + 1/ε3
2. ε1·ε2/ε3
3. ε1 + ε2 − ε3
4. ε1 + ε2 + ε3

Answer: ε1 + ε2 + ε3

The total error in a cascaded system is the sum of the individual errors from each subsystem, as each error contributes independently to the overall output error.

Q3. The steady state error of a unity feedback linear system for a unit step input is 0.1. The steady state error of the same system, for a pulse input r(t) having a magnitude of 10 and a duration of one second, as shown in the figure is

1. 0
2. 0.1
3. 1
4. 10

Answer: 0

For a pulse input, the system can respond fully to the input during the duration of the pulse, allowing it to reach the desired output level without any steady state error. Since the pulse input has a magnitude of 10 and lasts for one second, the system can achieve the output of 10, resulting in a steady state error of 0.