Test: Different Of Circuit


40 Questions MCQ Test Basic Electrical Technology | Test: Different Of Circuit


Description
This mock test of Test: Different Of Circuit for Electrical Engineering (EE) helps you for every Electrical Engineering (EE) entrance exam. This contains 40 Multiple Choice Questions for Electrical Engineering (EE) Test: Different Of Circuit (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Different Of Circuit quiz give you a good mix of easy questions and tough questions. Electrical Engineering (EE) students definitely take this Test: Different Of Circuit exercise for a better result in the exam. You can find other Test: Different Of Circuit extra questions, long questions & short questions for Electrical Engineering (EE) on EduRev as well by searching above.
QUESTION: 1

The instantaneous voltage is a product of the resistance and the _____________ current in a resistive circuit.

Solution:

The instantaneous voltage is a product of the instantaneous current and the resistance in the circuit.

QUESTION: 2

Find the value of the instantaneous voltage if the resistance is 2 ohm and the instantaneous current in the circuit is 5A.

Solution:

We know that,
v=iR, substituting the given values from the question, we get v=10V.

QUESTION: 3

The power for a purely resistive circuit is zero when?

Solution:

The power in a resistive circuit is the product of the voltage, current and the cosine of the phase angle. Hence if either voltage or current is zero, the power is zero.

QUESTION: 4

If the maximum voltage in the circuit is 10V and the resistance is 5 ohm, calculate the maximum current in the circuit.

Solution:

We know that:
Im=Vm/R
Substituting the given values from the question, we get Im=2A.

QUESTION: 5

Calculate the resistance in the circuit if the rms voltage is 20V and the rms current is 2A.

Solution:

We know that:
R=V/I
Substituting the given values from the question, we get R=10 ohm.

QUESTION: 6

 The power for a purely resistive circuit is zero when?

Solution:

P=VIcosϕ Power in a circuit is the product of voltage, current and the cosine of the phase angle. Phase angle is 00 for purely resistive circuit so, P=VI. Hence if either voltage or current is zero, the power is zero.

QUESTION: 7

Can ohm’s law be applied in an ac circuit?

Solution:

 Ohm’s law can be applied in ac as well as dc circuits. It can be applied in ac circuits because the condition V=IR holds true even in ac circuits.

QUESTION: 8

 What is the current found by finding the current in n equidistant regions and dividing by n?

Solution:

The average value of current is the sum of all the currents divided by the number of currents.

QUESTION: 9

 What is the effective value of current?

Solution:

Effective current is also known as the effective current. RMS stands for Root Mean Square. This value of current is obtained by squaring all the current values, finding the average and then finding the square root.

QUESTION: 10

Find the average value of current when the current that are equidistant are 4A, 5A and 6A.

Solution:

The average value of current is the sum of all the currents divided by the number of currents. Therefore average current= (5+4+6)/3=5A.

QUESTION: 11

 In case of Inductive circuit, Frequency is ______________ to the inductance.

Solution:

The formula for frequency in an inductive circuit is:
XL=2*pi*f*L.
Therefore: L is inversly proportional to f.

QUESTION: 12

If the current and voltage are 90 degree out of phase, the power factor will be?

Solution:

The power factor is the cosine of the angle in between the voltage and the current. If the angle between the voltage and current is 90, then cos90=0. Hence, the power factor is zero.

QUESTION: 13

If the power factor is 1/10 and the value of impedance is 20 ohm, calculate the resistance in the circuit.

Solution:

We know that:
cos(ϕ) = R/Z
R = Z cos(ϕ) = 20/10 = 2 ohm.

QUESTION: 14

What is the unit for inductive reactance?

Solution:

Inductive reactance is nothing but the impedance. Impedance is the AC equivalent of resistance, hence the unit for inductive reactance is ohm.

QUESTION: 15

If the current in a coil having a constant inductance of L henrys grows at a uniform rate, what is the value of the average current?

Solution:

The average current is the average of the current which flows in the inductor. Hence it is I/2.

QUESTION: 16

  It is preferable to connect bulbs in series or in parallel?

Solution:

Bulbs are connected in parallel so that even if one of the bulbs blow out, the others continue to get a current supply.

QUESTION: 17

Calculate the emf induced in an inductor if the inductance is 10H and the current is 2A in 4s.

Solution:

The expression for emf in an inductive circuit is:
emf= LI/t
Substituting the values from the given question, we get emf= 5V.

QUESTION: 18

 Calculate the current in an inductor if the energy stored is 160J and the inductance is 20H.

Solution:

The expression for energy in an inductor is:
W= LI2/2t
Substituting the values from the given question, we get I=4A.

QUESTION: 19

Find the time taken for the current in an inductor to change to 2A from 0A if the power in the inductor is 5W. The value of inductance is 10H.

Solution:

The expression for power in an inductive circuit is:
P= LI2/2
Substituting the values from the given question, we get t=4s.

QUESTION: 20

An induced emf is said to be?

Solution:

Any circuit in which a change of current is accompanied by a change of flux, and therefore by an induced emf, is said to be inductive.

QUESTION: 21

 What is the relation between current and voltage in a capacitor?

Solution:

Current=rate of change of charge=> I=dQ/dt. Q=CV, hence I=CdQ/dt.

QUESTION: 22

Calculate the current in the capacitor having 2V supply voltage and 3F capacitance in 2seconds.

Solution:

 Q is directly proportional to V. The constant of proportionality in this case is C, that is, the capacitance. Hence Q=CV.
Q=3*2=6C.
I=Q/t= 6/2=3A.

QUESTION: 23

 If 2V is supplied to a 3F capacitor, calculate the chance stored in the capacitor.

Solution:

Q is directly proportional to V. The constant of proportionality in this case is C, that is, the capacitance. Hence Q=CV.
Q=3*2=6C.

QUESTION: 24

 Which among the following expressions relate charge, voltage and capacitance of a capacitor?

Solution:

Q is directly proportional to V. The constant of proportionality in this case is C, that is, the capacitance. Hence Q=CV.

QUESTION: 25

What happens to the current flow in a fully charged capacitor?

Solution:

When a capacitor is fully charged, it does not store any more charge. There is no change in charge with time. Current is the rate of change of charge, hence it becomes zero, or stops.

QUESTION: 26

For high frequencies of alternating current, capacitor acts as?

Solution:

Capacitive impedance is inversely proportional to frequency. Hence at very high frequencies, the impedance is almost equal to zero, hence it acts as a short circuit and there is no voltage across it.

QUESTION: 27

For very low frequencies of alternating current, capacitor acts as?

Solution:

Capacitive impedance is inversely proportional to frequency. Hence at very low frequencies the impedance is almost infinity and hence acts as an open circuit and no current flows through it.

QUESTION: 28

 Capacitor preferred when there is high alternating current frequency in the circuits is?

Solution:

Mica capacitors are preferred for high frequency circuits because they have low ohmic losses and less reactance.

QUESTION: 29

 If a 2F capacitor has 1C charge, calculate the voltage across its terminals.

Solution:

Q is directly proportional to V. The constant of proportionality in this case is C, that is, the capacitance.

Hence Q = CV.

V = Q/C = 1/2

V = 0.5V.

QUESTION: 30

What is the voltage across a capacitor at the time of switching, that is, when t=0?

Solution:

At the time of switching, when t=0, the capacitor acts as a short circuit. The voltage across a short is always equal to zero hence the voltage across the capacitor is equal to zero.

QUESTION: 31

Find the total voltage applied in a series RLC circuit when i=3mA, VL=30V, VC=18V and R=1000 ohms.

Solution:
QUESTION: 32

 In an parallel RLC circuit, which of the following is always used as a vector reference?

Solution:

In an parallel RLC circuit, the voltage is always used as a reference and according to the phase of the voltage, the phase of the other parameters is decided.

QUESTION: 33

In an RLC circuit, the power factor is always ____________

Solution:

In an RLC series circuit, the power factor depends on the number of resistors and inductors in the circuit, hence it depends on the circuit.

QUESTION: 34

In an RLC series phasor, we start drawing the phasor from which quantity?

Solution:

In an RLC series phasor diagram, we start drawing the phasor from the quantity which is common to all three components, that is the current.

QUESTION: 35

What is the correct expression for the phase angle in an RLC series circuit?

Solution:

from the impedance triangle we get tanφ=(XL-XC)/R.
Hence φ=tan-1 (XL-XC)/R.

QUESTION: 36

When is tanφ positive?

Solution:

 tanφ is positive when inductive reactance is greater than capacitive reactance because current will lag the voltage.

QUESTION: 37

When is tanφ negative?

Solution:

tanφ is positive when inductive reactance is less than capacitive reactance because current will lead the voltage.

QUESTION: 38

 When is current in phase with the voltage?

Solution:

The current is in phase with the voltage when the capacitive reactance is in phase with the inductive reactance.

QUESTION: 39

What is resonance condition?

Solution:

The current is in phase with the voltage when the capacitive reactance is in phase with the inductive reactance. This is known as resonance condition.

QUESTION: 40

What is the frequency in resonance condition?

Solution:

At resonance condition, the frequency is maximum since the inductive reactance is equal to the capacitive reactance and the voltage and current are in phase.