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Electronics and Communication Engineering - Measurements and Instrumentation

Exercise : Measurements and Instrumentation - Section 3
41.

Assertion (A): Thermocouple instruments can be used for ac only.

Reason (R): Thermocouple instrument has a non linear scale.

Both A and R are true and R is correct explanation of A
Both A and R are true but R is not correct explanation of A
A is true R is false
A is false R is true
Answer: Option
Explanation:

Thermocouple Instrument can be used for both ac and dc.

42.
A meter has a resistance of 1 Ω and full scale deflection current of 1 mA. To convert into an ammeter of 1 A range, the shunt resistance should be
1000 Ω
1 Ω
0.01 Ω
0.001 Ω
Answer: Option
Explanation:

Resistance of shunt

.

43.
Two wattmeter method is suitable only for balanced loads.
True
False
Answer: Option
Explanation:

It is suitable for both balanced and unbalanced loads.

44.
A rectifier voltmeter using bridge rectifier and PMMC meter is calibrated to read rms value of sine wave. A triangular wave is applied to it and it reads 6.82 V. The rms value of triangular wave is
about 6.82 V
about 7.1 V
about 6.5 V
about 10 V
Answer: Option
Explanation:

Peak value of triangular wave is twice average value = 2 x 6.144 = 12.288 V rms value of triangular wave is peak value divided by 3 .

Therefore, reading .

45.
A radiation thermometer is suitable for temperatures
below 500°C
below 100°C
above 500°C
above 1400°C
Answer: Option
Explanation:

It is suitable for only very high temperatures.

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