1. State whether the following assertions are True or False.

Leakage flux exists only in primary circuit of a transformer.

Speed control of a 3-phase induction motor by stator voltage control is possible, if load torque increases with speed.

In a 3-phase delta connection, line current is equal to J3 times the phase current.

Average value of a sinusoidal ac is slightly greater than its rms value.

At series resonance, the current is maximum.

In pure inductive circuit, actual power is infinite.

Thevenin's theorem is true for both ac and dc circuits.

Op-Amp 741 can be used as a microprocessor.

NAND gate can be used as an amplifier.

Diode is a three terminal device.

Attempt any three questions from this section.

State and explain Thevenin's theorem with a suitable example.

Find the current in R1 of the network shown in Figure 1.

<img src='./qimages/15853-2b.jpg'>

For the output waveform of a half-wave rectifier shown in Figure determine

rms value,

average value,

form factor.

<img src='./qimages/15853-3a.jpg'>

Draw and explain resonance curve in series RLC circuit.

Derive the relationship between flux, reluctance and magnetic field intensity of a typical magnetic circuit.

A cast steel magnetic structure made of a bar of cross-section 4 cm2 is shown in Figure 3. Find the current that the 500 turn magnetizing coil on the left limb should carry so that a flux of 2 mWb is produced in the right limb. Iron has M as 600.

<img src='./qimages/15853-4b.jpg'>

Name any three methods of starting a three phase squirrel cage induction motor. Briefly explain anyone method.

What is servo motor? How does a dc servo motor differ from a conventional dc motor?

A 3-phase 50 Hz, 6-pole induction motor rotates at a speed of 950 rpm. Calculate slip and frequency of rotor induced emf.

Explain the concept of power in ac circuits. Draw power triangle and explain it.

If a coil of 150 turns is linked with a flux of 0·01 Wb when carrying a current of 10 amp, calculate the inductance of the coil.

Give the architecture of 8085 microprocessor. Explain the different buses and registers.

Explain stack pointer, program counter and flags in 8085.

Draw and the electronic circuit of a common emitter amplifier using BJT.

Explain the working of an inverting integrator using op-amp.

Describe a typical S-R flip-flop. Explain its working principle.

Draw and explain a 3-element shift register using D flip-flop.

10.(a) Explain the use of 555 timer as astable multivibrator.

Draw and explain a 6-bit binary weighted DAC.

11.(a) Draw the switch configuration, truth table and symbol of a tri-state inverter.

Explain the following instructions:

LDAX

SUI

CMA