21. Consider the following statements for PMMC Instruments:

1. The scale is non-uniformly divided
2. The power consumption is very low as 25 𝜇W to 200 𝜇W
3. The torque-weight ratio is high which gives a high accuracy

Which of the above statements are correct?
(a) 1 and 2 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2 and 3

Answer: (c)

22. The lagging loads when connected to the electrodynamometer wattmeter cause the wattmeter reading to:
(a) Read high
(b) Have no effect
(c) Read low
(d) Zero

Answer: (a)

23. The power flowing in a 3-phase, 3-wire balanced load system is measured by two wattmeter method. The reading of wattmeter 𝐴 is 7500 𝑊 and of wattmeter 𝐵 is −1500 𝑊. The power factor of the system will be nearly:
(a) 0.9
(b) 0.7
(c) 0.6
(d) 0.4

Answer: (d)

24. The self-capacitance of a coil is measured by a 𝑄 meter. The circuit is set into resonance at 2 MHz and the tuning capacitor is 460 𝑝F. The frequency is now adjusted to 4 MHz and resonance conditions are obtained the tuning capacitor at 100 𝑝F . The value of self-capacitance of the coil will be:
(a) 20 𝑝F
(b) 30 𝑝F
(c) 40 𝑝F
(d) 50 𝑝F

Answer: (a)

25. A coil with a resistance of 10 Ω is connected in the direct-measurement mode. Resonance occurs when the oscillator frequency is 1.0 MHz and the resonating capacitor is set at 65 𝑝F. The percentage error introduced in the calculated value of 𝑄 by 0.02Ω insertion resistance will be:
(a) 0.1 %
(b) 0.2 %
(c) 0.3 %
(d) 0.4 %

Answer: (b)

26. If two time varying signals of equal amplitude and 270° phase displacement are applied to X and Y plates of CRO, the display will be:
(a) A straight line
(b) An ellipse
(c) A circle
(d) A rectangle

Answer: (c)

27. If the bandwidth of an oscilloscope is given as direct current to 10 MHz. The fastest rise time a sine wave can have to be accurately reproduced by an instrument will be:
(a) 20 ns
(b) 25 ns
(c) 30 ns
(d) 35 ns

Answer: (d)

28. In a transducer, the observed output deviates from the correct value by a constant value the resulting error is called:
(a) Zero error
(b) Sensitivity error
(c) Non-conformity error
(d) Hysteresis error

Answer: (b)

29. The output of transducer depending not only on present input quantity but also depends on input quantities previously applied to it. This property of transducer is called:
(a) Causality
(b) Hysteresis
(c) Stress
(d) Non-elasticity

Answer: (b)

30. How many bits are in an ASCII code?
(a) 4
(b) 7
(c) 9
(d) 11

Answer: (b)