Technical Question for Electrical Engineering

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129) The unit of inductance is Henry. It can also be represented as

A. V/Sec

B. V - Sec

C. V/A

D. V - Sec/A

 A  B  C  D

We know the induced voltage in an inductive circuit of inductance L, is V = Ldi/dt
Where, L is proportional constant known as inductance
From above expression we get, L = Vdt/di
So, from above equation, it can be concluded that, unit of inductance henry is volt - sec /A

130) The energy stored in an inductor of inductance L Henry is represented as,

A. i2L

B. iL2

C. (1/2)L.i2

D. L2/i

 A  B  C  D
The voltage in an inductor is given as

v = L di
dt

Therefore, instantaneous power p entering the inductor at any instant is given by

p = vi = Li di
dt

Hence, the energy stored in the inductor,

   
W = p.dt = Li.di
   
= 1 Li2 Joule
2

131) The instantaneous power in an inductor is proportional to the

A. inductance, instantaneous current, rate of change of current.

B. inductance, rate of change of current.

C. inductance, instantaneous current.

D. only rate of change of current.

 A  B  C  D
The voltage of inductor is given by v = L di
dt
Therefore, expression of power will be p = vi = Li di
dt
Therefore, power is proportional to L, i and di
dt

132) The voltage induced in an inductor of L Henry is represented as,

A. Li

B. L di/dt

C. L/i

D. L2i

 A  B  C  D
The expression of voltage across an inductor of inductance L is given by v = L di
dt
where ratio of change of current with respect to time is di
dt

133) Absolute permittivity of a dielectric medium is represented by

A. εo / εr

B. εoεr

C. εr / εo

D. none of the above

 A  B  C  D

The absolute permittivity of a dielectric medium is expressed as ε = εoεr

Where, εo is the permittivity of free space and εr is the relative permittivity of the medium.

134) A parallel plate capacitor has a capacitance of C farad. It area of the plates is doubled and the distance between them is half, the capacitance of the capacitor is

A. 1C farad

B. 2C farad

C. 4C farad

D. 16C farad

 A  B  C  D

A capacitor consists of two parallel places separated by a dielectric material. It the area of the plates is A m2 and the distance between them is d meter, the capacitance C is given by C = (εA)/d
Where A is the area of the plates & d is distance between the plates. From the above expression of capacitance it is obvious that, if area is doubled and distance is half the capacitance will become 4 times.

135) Which of the followings is the expression for energy stored in a capacitor

A. Cv

B. C dv/dt

C. C/v

D. (1/2)Cv2

 A  B  C  D
Therefore, the instantaneous power in the capacitor is given by p=iv

       
∴ Energy stored in capacitor is given by pdt = ivdt = C.v.dv
     
= 1 Cv2 Joule
2

136) A 2m long conductor, carries a current of 50A at a magnetic field of 100 x 10 − 3T. The force on the conductor is

A. 10 N

B. 100 N

C. 1000 N

D. 10000 N

 A  B  C  D

The magnetic of the force on the conductor, F in the case of conductor of length l meter arranged at right angles to the magnetic field B tes la and carrying a current I, is given by F = B I P

137) A branch of a network is said to be active when it consists of one

A. resistor

B. voltage source

C. inductor

D. capacitor

 A  B  C  D

When a branch of a network contains one or more sources it is called an active branch.

138) A branch of a network is said to be passive when it contains

A. Voltmeter

B. voltage source

C. current source

D. Battery

 A  B  C  D

A branch that does not contain any source is known as a passive branch. Voltmeter is not a source.

139) Which of the following is not a bilateral?

A. resistor

B. diode

C. capacitor

D. inductor

 A  B  C  D

A bilateral element conduct equally well in either directions. Such as resistor & inductor . When the current voltage relation are different for the two directions of current flow, the element is said to be unilateral Diode is a unilateral element.

140) Which of the following characteristics is attributed to an ideal independent voltage source?

A. Independent of magnitude of current supplied

B. dependent of the magnitude of current supplied

C. dependent of the direction of flow of current

D. None of above

 A  B  C  D

In independent ideal voltage source is such a source, which gives fixed voltage, irrespective of magnitude and direction of current flowing through it.

141) Dependent source of current and voltage are those which have,

A. Unidirectional characteristic.

B. Output dependent on input

C. Independent of any other network variable.

D. all above.

 A  B  C  D

The source whose output voltage or current is a function of the voltage or current in another part of the circuit is called dependent source.

142) The internal resistance of a practical voltage source is considered to be connected in

A. series

B. parallel

C. either parallel or series

D. none of the above

 A  B  C  D

When ever load is connected to the voltage source, its terminal voltage decreases become of its internal resistance. Hence the internal resistance of a practical voltage source is assumed to be connected in series with the source.

143) Whenever current is supplied by a source its terminal voltage

A. increases

B. decreases

C. remains constant

D. increases exponentially.

 A  B  C  D

Whenever current is supplied by a source, this current also flows through the internal resistance connected in series in the source. Because of voltage drop across the internal resistance, the terminal voltage is decreased.

144) When a numbers of different valued resistance are connected in series, the voltage drop across each of the resistor is

A. proportional to resistance

B. proportional to current

C. proportional to square of current

D. equal

 A  B  C  D
Let V is the source voltage and R1, R2, R3, ……… Rn resistances are connected in series, across the source of voltage V. Therefore, the current through the resistances will be
V = I
R1 + R2 + R3 + ......+ Rn

Therefore, V1 = IR1, V2 = IR2, V3 = IR3 ……..Vn = IRn. That means Vn ∝ Rn

So, voltage drop across each resistance will be proportional to their resistive values.

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