1) Electrical equipments are generally earthed through an electrode to avoid shocks when someone touches the body of the equipment. The earth resistance is effected by
a. Depth of electrodes buried in the soil
b. Shape and material of earth electrodes
c. Specific resistance of the soil surrounding the electrode
d. All of these
e. None of these
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Answer
Explanation
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ANSWER: All of these
Explanation:
No explanation is available for this question!
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2) A highly sensitive galvanometer is used in Wheatstone bridge and it can detect a current as low as 80 pA. The resistances of each arm of bridge are 800 ohm and the resistance of galvanometer is 40 ohm. If an input of 20 V is applied to the bridge then the smallest change in resistance which can be detected is
a. 10.752 μA
b. 15.280 μA
c. 17.351 μA
d. 23.719 μA
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Answer
Explanation
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ANSWER: 10.752 μA
Explanation:
No explanation is available for this question!
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3) The resistances of the various arms of Wheatstone bridge are P = 500 ohm, Q = 50 ohm, R = 1010 ohm and S = 100 ohm. The emf of the batter is 5 V and the current sensitivity of galvanometer is 8 mm / μ A. If the internal resistance of the galvanometer is 80 ohm then the deflection of galvanometer and the sensitivity of the bridge in terms of deflection per unit change of resistance are
a. 151.2 mm, 30.24 mm / ohm
b. 100 mm, 21.03 mm / ohm
c. 186 mm, 40.37 mm / ohm
d. 193 mm, 20.74 mm / ohm
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Answer
Explanation
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ANSWER: 151.2 mm, 30.24 mm / ohm
Explanation:
No explanation is available for this question!
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4) When a voltmeter - ammeter method is applied for the measurement of resistance, the voltmeter reads a value of 8.28 V and the ammeter reading is 4.14 mA. Then the value of the resistance will be
a. 2 kΩ
b. 2.0 kΩ
c. 2.00 kΩ
d. 2.000 kΩ
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Answer
Explanation
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ANSWER: 2.00 kΩ
Explanation:
No explanation is available for this question!
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5) During a test, the strain gauge with resistance of 200 ohm undergoes a change of 0.120 ohm and the strain of the gauge is 1.2 X 10 -4. Then the gauge factor will be
a. 4
b. 5
c. 4.5
d. 6
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Answer
Explanation
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ANSWER: 5
Explanation:
No explanation is available for this question!
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6) The earth resistance can be measured by
a. Fall of potential method
b. Using an earth tester
c. Ducter ohmmeter method
d. Only (a) and (b)
e. All the above
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Answer
Explanation
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ANSWER: Only (a) and (b)
Explanation:
No explanation is available for this question!
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7) In a slide wire potentiometer, for a voltage source of 1.012 V the jockey is kept at 101.2 cm. If the potentiometer has 20 wires of 1 m each and the resistance of wires is 800 ohm, then the value of the working current is
a. 15 mA
b. 20 mA
c. 25 mA
d. 27 mA
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Answer
Explanation
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ANSWER: 25 mA
Explanation:
No explanation is available for this question!
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8) For the measurement of low resistances from few ohms down to one micro ohm, which of the following instrument is not suitable?
a. Potentiometer method
b. Ammeter – voltmeter method
c. Ohmmeter
d. Kelvin double bridge method
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Answer
Explanation
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ANSWER: Ohmmeter
Explanation:
No explanation is available for this question!
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9) For the measurement of low resistances, Kelvin’s double bridge has high accuracy because
a. It has two set of ratio arms which eliminates effect of resistance of connecting lead
b. It has a null indicating galvanometer
c. It has two null indicator
d. It has four sets of ratio arms which eliminates the effect of resistance of connecting lead
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Answer
Explanation
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ANSWER: It has two set of ratio arms which eliminates effect of resistance of connecting lead
Explanation:
No explanation is available for this question!
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10) The method / methods suitable for the measurement of low resistance is / are
a. Ammeter - voltmeter method
b. Kelvin’s double bridge method
c. Potentiometer method
d. All of these
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Answer
Explanation
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ANSWER: All of these
Explanation:
No explanation is available for this question!
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