A Wein bridge oscillator is shown in figure. Which of the following statements are true if $$'f'$$ is the frequency of oscillation?

The transfer function for the state variable representation $$\mathop X\limits^ \bullet = AX + BU,\,\,Y = CX + DU,$$ is given by

Consider a second order system whose state space representation is of the form $$\mathop X\limits^ \bullet = AX + BU.$$ If $$\,{x_1}\,\,\left( t \right)\, = {x_2}\,\left( t \right),$$ then system is

Signal flow graph is used to obtain the

Three devices $$A,$$ $$B$$ and $$C$$ have to be connected to a $$8085$$ microprocessor. Device $$A$$ has highest priority and device $$C$$ has the lowest priority. In this context which of the following is correct assignment of interrupt inputs?

A $$10$$ bit $$A/D$$ converter is used to digitize an analog signal in the $$0$$ to $$5$$ $$V$$ range. The maximum peak to peak ripple voltage that can be allowed in the $$D.C.$$ supply voltage is

The following circuit (Fig.) resonates at

In the following circuit (Fig.) $$i(t)$$ under steady state is

A $$CRO$$ screen has ten divisions on the horizontal scale. If a voltage signal $$5$$ $$sin$$$$\left( {314t + {{45}^ \circ }} \right)$$ is examined with a line base setting of $$5$$ $$msec/div,$$ the number o0f cycles of signal displayed on the screen will be

V_RN, V_YN and V_BN are the instantaneous line to neutral voltages and i_R, i_Y and i_B are instantaneous line currents in a balanced three-phase circuit, the computation, V_RN (i_y $$-$$ i_B) $$-$$ (V_YN $$-$$ V_BN) i_R will yield a quantity proportional to

A metal strain gauge has gauge factor of two, it's nominal resistance is $$120$$ Ohms. It is undergoes a strain of $${10^{ - 5}},$$ the value of change of resistance in response to the strain is

A $$220/440$$ $$V,$$ $$50$$ $$Hz$$ single phase transformer operates on $$220$$ $$V,$$ $$40$$ $$Hz$$ supply with secondary winding. Then

A cumulative compounded long shunt motor is driving a load at rated torque and rated speed. If the series field is shunted by a resistance equal to the resistance of the series field, keeping the torque constant.

Two $$550$$ $$kVA$$ alternators operate in parallel to supply the following loads
$$(i)$$ $$250$$ $$kW$$ at $$0.95$$ power factor lag
$$(ii)$$ $$100$$ $$kW$$ at $$0.8$$ power factor lead one machine is supplying $$200kW$$ at $$0.9$$ power factor lag. The power factor of the other machine must be

A synchronous motor operates at $$0.8$$ $$p.f.$$ lagging. If the field current of the motor is continuously increased

$$(1)$$ the power factor decreases upto a certain value of field current and thereafter it increases
$$(2)$$ the armature current increases upto a certain value of field current and thereafter it decreases
$$(3)$$ the power factor increases upto a certain value of field current and thereafter it decreases
$$(4)$$ the armature current decreases upto a certain value of field current and thereafter it increases. From these the correct one is

A three phase alternator has negligible stator resistance. A short circuit test is conducted on this alternator. At a particular speed a field current of $${{\rm I}_f}$$ is required to drive the rated armature current. If the speed of the alternator is reduced to half, the field current required to maintain rated armature current

A three phase slip ring induction motor is fed from the rotor side with stator winding short circuited. The frequency of the currents flowing in the short circuited stator is

The line integral of the vector potential A around the boundary of a surface S represents

Given the differential equation $${y^1} = x - y$$ with initial condition $$y(0)=0.$$ The value of $$y(0.1)$$ calculated numerically upto the third place of decimal by the $${2^{nd}}$$ order Runge-Kutta method with step size $$h=0.1$$ is

A chopper operating at a fixed frequency is feeding an $$R$$-$$L$$ load. As the duty ratio of the chopper is increased from $$25\% $$ to $$75\% $$, the ripple in the load current

When a line commutated converter operates in the inverter mode

The thermal resistance between the body of a power semiconductor device and the ambient is expressed as

In load flow analysis, the load connected at a bus is represented as

The distribution system shown in figure is to be protected by over current system of protection. For proper fault discrimination directional over current relays will be required at locations

The transient stability of the power system can be effectively improved by

A three phase overhead transmission line has its conductors horizontally spaced with spacing between adjacent conductors equal to 'd'. If now the conductors of the line are rearranged to form an equilateral triangle of sides equal to 'd' then

$$s(t)$$ is step response and $$h(t)$$ is impulse response of a system. Its response $$y(t)$$ for any input $$u(t)$$ is given by