Questions and Answers on Electrical Engineering

1. Does conductivity in a conductor change with change in temperature?
Ans. Yes. Resistivity in a conductor is directly proportional to temperature. If temperature decreases resistance will also decrease
2. What are the properties of soft iron?
Ans. i. it is a magnetic material
         ii.it has low coercivity and so does not remain magnetised when the field is removed
         iii. it cannot be used for permanent magnets.
3. What is the condition for distortionless transmission line?
Ans. RC=LG
          Resistance*Capacitance=inductance*conductance
4. What is VSWR?
Ans. Voltage standing wave ratio (VSWR) is the ratio between maximum voltage to minimum voltage.
         VSWR=Vmax/Vmin
5. What is the formula for flux density?
Ans. flux density=flux/area coulombs/m^2
6. What is the formula for electric field intensity?
Ans. H=Force in newtons/charge in coulombs.
7. What is coulombs law?
Ans.i. like charges repel each other whereas unlike charges attract each other.
       ii. force experienced is directly proportional to the product of the charges  and inversely proportional to square of the distance between them.
        F=K*Q1*Q2/D^2
 Where K=1/4pi*e0*er
8. What is the formula for voltage divider?
Ans. Vout=Vin(Rx/(Rx+R1+R2+....)
        Where vout is the voltage across the resistor whose voltage drop has to be found
                    Vin is the input voltage
                    Rx is the resistor whose resistance has to be found
                    R1,R2,R3.... are the total resistors in the circuit.
9.what is the formula to find the equation of a circle?
Ans. (x-h)^2+(y-k)^c=r^2
 where h and k are the centre of the circle and r is the radius of the circle
10.What is Barkhausen's criterion ?
Ans.In electronics the Barkhausen stability criterion is a mathematical condition to determine when a linear electronic circuit  will oscillate.
     

1. The loop gain is equal to unity in absolute magnitude, that is, ${\displaystyle |\beta A|=1\,}$ and
2. The phase shift  around the loop is zero or an integer multiple of 2π: ${\displaystyle \angle \beta A=2\pi n,n\in 0,1,2,\dots \,.}$

11.What is the formula to find joule?

Ans. Joule=watt*seconds