A dynamometer wattmeter is connected in ac circuit. The measured power is rms po

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Question
A dynamometer wattmeter is connected in ac circuit. The measured power is
Options
A. rms power
B. average power
C. peak power
D. instantaneous power

Correct Answer

average power

Explanation

All wattmeters measure average power over a cycle.

Measurements and Instrumentation problems

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2. In a strain measuring device using a strain gauge, the output quantity is
Options
A. voltage
B. resistance
C. impedance
D. either (a) or (b)

3. In a ballistic galvanometer, a charge of 100 ?C gives a first swing of 25�. The charge required to cause first swing of 50� is
Options
A. 200 ?C
B. 400 ?C
C. 50 ?C
D. 25 ?C

4. The coil of a moving iron instrument has a resistance of 500 ? and an inductance of 1 H. It reads 250 V when a 250 V dc is applied. If series resistance is 2000 ?, its reading when fed by 250 V, 50 Hz ac will be
Options
A. 260 V
B. 252 V
C. 250 V
D. 248 V

5. In a CRO which of the following is not a part of electron gun
Options
A. cathode
B. grid
C. accelerating anode
D. X - Y plates

6. A meter with a resistance of 100 ? and a full scale deflection of current of 1 mA is to be converted into voltmeter of 0 - 5 V range. The multiplier resistance should be
Options
A. 490 ?
B. 5000 ?
C. 4900 ?
D. 5100 ?

7. A dynamometer wattmeter is connected in ac circuit. The reading will be
Options
A. V-A product
B. average power
C. peak power
D. instantaneous power

9. Which of the following voltmeters would you use for measuring voltage across 20 k? resistance?
Options
A. Voltmeter having a resistance of 5 k?
B. Voltmeter having a sensitivity of 1 kW/V
C. Voltmeter having sensitivity of 10 kW/V
D. None of the above

10. Potentiometer method of dc voltage measurement is more accurate than direct measurement using a voltmeter because
Options
A. it loads the circuit to maximum extent
B. it loads the circuit moderately
C. it does not load the circuit at all
D. it uses centre zero galvanometer instead of Voltmeters

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