Basic Electrical and Electronics Engineering-II by S. K. Bhattacharya | 9789332509726 | 9332509727 | Holooly

Electronics and Electrical

Basic Electrical and Electronics Engineering-II

189 SOLVED PROBLEMS

Question: 9.9

Find the output voltage of the three-input summing amplifier circuit shown in Fig. 9.27. ...

Verified Answer:

Considering the ratios of

R_{f} /R

...

Question: 4.8

A four-pole dc generator has 1000 conductors. The flux per pole is 25 mWb. Calculate the EMF induced when the armature is lap connected and run at 1500 rpm. At what speed the generator must be driven to produce the same EMF with the armature winding wave connected? ...

Verified Answer:

Case I P = 4, Z = 1000,

Φ = 25 × 10^{−3} W...

Question: 3.25

A 10 kVA 440/220 V, 50 Hz single-phase transformer gave the following test results when both the following tests were conducted on the high-voltage side: Open circuit test : 440 V, 1.0 A, 100 W Short circuit test : 20 V, 22.7 A, 130 W. Using the test data, calculate the efficiency and voltage ...

Verified Answer:

Full-load current on the high-voltage side = [late...

Question: 4.2

A four-pole dc generator having wave wound armature winding has 51 slots, each slot containing 20 conductors. Calculate the voltage generated in the armature when driven at 1500 rpm. Assume flux per pole to be 0.5 mWb. ...

Verified Answer:

P = 4, A = 2 (because the armature winding is wa...

Question: 4.1

A 220 V, 50 kW dc shunt generator was run as a motor on no load at rated speed. The current drawn from the line was 8 A and the shunt field current was 2 A. The armature resistance of the machine is 0.1 Ω. Calculate the efficiency of the generator at full load. ...

Verified Answer:

Input power at no load = VI = 220 × 8 = 1760 W Iro...

Question: 3.26

A 440/220 V single-phase transformer has percentage resistance drop and reactance drop of 1.2 per cent and 6 per cent, respectively. Calculate the voltage regulation of the transformer at 0.8 power factor lagging. ...

Verified Answer:

Percentage voltage regulation

=\frac{(I...

Question: 8.2

The open-loop gain of an amplifier changes by 10 per cent due to the effect of temperature, ageing, etc. A change in gain of not more then 2 per cent is allowed. If the amplifier gain with feedback is 100, find the minimum value of feedback ratio. ...

Verified Answer:

We know,

A_{f}=\frac{A}{1+ \b...

Question: 8.1

Calculate the closed-loop gain of a negative feedback amplifier with A = 10,000 and β = 0.01. Show that the closed-loop gain does not change much even when the gain of the basic amplifier is changed by ± 50 per cent. ...

Verified Answer:

A_{f}=\frac{A}{1+A \beta }

...

Question: 7.11

The saturation drain current of an enhancement MOSFET is 6 mA when gate-source voltage is 5 volts. The threshold voltage is 3 volts. Calculate the saturation drain current for a gate source voltage of 10 volts. ...

Verified Answer:

The drain current,

I_{D} = K (V_{GS} – V_{T...

Question: 7.8

An n-channel JFET has the following parameters: IDSS = 10 mA and Vp = -3.5Vp . What will be the value of the drain current ID when VGs = -2.5 V? ...

Verified Answer:

I_{D}=I_{DSS}\left[1-\frac{V_{GS}}{V_{p}} \...

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