Electronics and Communication Engineering - Measurements and Instrumentation

1. 

The current in a circuit is measured using a 150 : 1 CT If the ammeter reads 0.6 A, the circuit current is

A. 250 A
B. 90 A
C. 156 A
D. 144 A

Answer: Option B

Explanation:

150 x 0.6 = 90 A.


2. 

A volt ratio box should have low resistance.

A. True
B. False

Answer: Option B

Explanation:

It should have high resistance.


3. 

A Hall effect transducer has KH = - 1 x 10-8. If B = 1 Wb/m2, I = 3 A and bismuth slab is 2 mm wide, the Hall voltage is

A. -7.5 x 10-6 V
B. -15 x 10-6
C. -20 x 10-4 V
D. -22.5 x 10-4 V

Answer: Option B

Explanation:

.


4. 

Two ammeters A and B both 0-10 A have internal resistance of 1 Ω and 0.5 Ω respectively. They are connected in parallel. If total current is 15 A, then

A. IA = IB = 7.5 A
B. IA = 5 A, IB = 10 A
C. IA = 10 A, IB = 5 A
D. IA = 9 A, IB = 6 A

Answer: Option B

Explanation:

Currents divide in inverse proportion of resistances.

.


5. 

Which of the following is not correct?

A. Voltmeter should have a very high resistance
B. An ammeter should have a very low resistance
C. A shunt should have a very low resistance
D. An electronic voltmeter draws appreciable current from source

Answer: Option D

Explanation:

An electronic voltmeter draws negligible current.


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