Electronic Instruments

21. The materil used to coat inside the face of CRT is ___________.

1. Carbon
2. Sulphur
3. Silicon
4. Phosphorous

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22. The most accurate device for measuring voltage is ___________.

1. Voltmeter
2. Multimeter
3. CRO
4. VTVM

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23. The resistance of an ideal voltmeter is ___________.

1. Low
2. Infinite
3. Zero
4. High

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24. The sensitivity of a multimeter is given in ___________.

1. O
2. Amperes
3. kO/V
4. none of the above

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25. The sensitivity of a voltmeter which uses a 100 µA meter movement is ___________.

1. 1 kO/V
2. 10 kO/V
3. 5 kO/V
4. Data insufficient

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26. To send 10% of the main current through a moving coil galvanometer of resistance 99 O the shunt required is ___________.

1. 11 O
2. 9 O
3. 100 O
4. 9 O

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27. Two multimeters A and B have sensitivities of 10 kO/V and 30 kO/V respectively. Then ___________.

1. Multimeter A is more sensitive
2. Multimeter B is more sensitive
3. Both are equally sensitive
4. None of the above

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28. What is the total resistance of a voltmeter on the 10 V range when the meter movement is rated for 50 µA of full-scale current?

1. 10 kO
2. 20 kO
3. 200 kO
4. None of the above

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29. When an ammeter is inserted in the circuit, the circuit current will ___________.

1. Increase
2. Decrease
3. Remain the same
4. None of the above

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30. Which of the following is likely to have the largest resistance?

1. Voltmeter of range 10 V
2. Moving coil galvanometer
3. Ammeter of range 1 A
4. A copper wire of length 1 m and diameter 3 mm

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