Electronic measurements and instrumentation miscellaneous Difficult Questions and Answers | Page - 6

Electronic measurements and instrumentation miscellaneous

Match List-I with List-II and select the correct answer using the codes given below the Lists:
List-I (Parameter measured) List-II (Bridge)
A. Audio frequency 1. Maxwell bridge
B. Hay bridge 2. 20
C. Dielectric loss 3. Wien bridge
D. Low Q inductor 4. Schering bridge

1. A B C D
  3 4 2 1
1. A B C D
  3 2 4 1
1. A B C D
  4 2 1 3
1. A B C D
  1 4 2 3

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● Audio frequency → Wien bridge
● High Q inductor → Hay bridge
● Dielectric loss → Schering bridge
● Low Q inductor → Maxwell bridge

Correct Option: B

● Audio frequency → Wien bridge
● High Q inductor → Hay bridge
● Dielectric loss → Schering bridge
● Low Q inductor → Maxwell bridge

A sinusoidal waveform, when observed on an oscilloscope, has a peak to peak ampltitude of 6 cm. If the vertical sensitivity setting is 5V/cm, the rms value of the voltage will be:

1. 10·6 V
1. 11·1 V
1. 12·6 V
1. 15 V

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Given,
Peak-to-peak = 6 cm
so,
peak value = 3 cm
sensitivity = 5 V/cm
∴ Amplitude of the signal
= 3 × 5 = 15V
r.m.s. value = Amplitude/√2
= 5/√12= 10·6V

Correct Option: A

Given,
Peak-to-peak = 6 cm
so,
peak value = 3 cm
sensitivity = 5 V/cm
∴ Amplitude of the signal
= 3 × 5 = 15V
r.m.s. value = Amplitude/√2
= 5/√12= 10·6V

A 35V dc supply is connected across a resistance of 600 ohm in series with an unknown resistance Rx. A voltmeter having a resistance of 1·2 k-ohm is connected across 600 ohm resistance and reads 5V. The value of resistance Rx will be:

1. 120 ohm
1. 400 ohm
1. 1·8 k-ohm
1. 2·4 k-ohm

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From the given information we can make the circuit arrangement given below:
Let current I is flowing in the circuit.
Here,
I = Voltmeter reading in volt
Effective resistance offered by the voltmeter

or
I = 5
600 | | 1200

or
I = 5 = 5 = 1 Amp
720000/1800 400 80

Now, R_x = 35 – 5/I
or
R_x = 30
1/80

or
R_x = 2400
or
R_x = 2·4 kΩ.

Correct Option: D

From the given information we can make the circuit arrangement given below:
Let current I is flowing in the circuit.
Here,
I = Voltmeter reading in volt
Effective resistance offered by the voltmeter

or
I = 5
600 | | 1200

or
I = 5 = 5 = 1 Amp
720000/1800 400 80

Now, R_x = 35 – 5/I
or
R_x = 30
1/80

or
R_x = 2400
or
R_x = 2·4 kΩ.

Potentiometer is, essentially, an apparatus by means of which:

1. Resistance are compared
1. Emf ’s are compared
1. Capacitances are compared
1. Currents are compared

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Potentiometer is, essentially an apparatus by means of which emf ’s are compared.

Correct Option: B

Potentiometer is, essentially an apparatus by means of which emf ’s are compared.

Siemens is a unit for measuring:

1. Conductance
1. Resistance
1. Flux density
1. Electric field

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Siemens is a unit for measuring conductance.

Correct Option: A

Siemens is a unit for measuring conductance.