IndiaBIX

Electronics and Communication Engineering - Measurements and Instrumentation

Exercise : Measurements and Instrumentation - Section 4
26.
A sinusoidal signal is measured by CRO. The scale is set at 4 mV/cm. If vertical distance between positive and negative peaks is 6 cm, the peak value of ac signal is
6 mV
12 mV
24 mV
3 mV
Answer: Option
Explanation:

, Peak to peak value will be 24 mV.

27.
Wheatstone bridge is suitable for low resistances.
True
False
Answer: Option
Explanation:

It is suitable for medium resistances.

28.
To avoid creep in an energy meter
two shading bands are put on shunt magnet
two shading bands are put on series magnet
two holes are cut in the disc on opposite sides of spindle
the potential coil is made of very thin wire
Answer: Option
Explanation:

When a hole comes under a pole of upper electromagnet the disc becomes stationary. Thus creep is avoided.

29.
A wire strain gauge has a gauge factor of 2, resistance of 125 Ω and length 1 m. If length of wire changes by .005 m, change in resistance will be
0.25 Ω
0.5 Ω
1.25 Ω
2.5 Ω
Answer: Option
Explanation:

.

30.
Four voltmeters have following specifications. If accuracy is main consideration which is the best?
100 V, 2 mA
100 V, 100 mA
100 V, 1 mA
100 V, 0.1 mA
Answer: Option
Explanation:

Since the current drawn is minimum, the accuracy is maximum.

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