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Question 1

When is a Wheatstone bridge considered balanced?

Answer 1

A Wheatstone bridge is balanced when the ratio of the two resistances in one leg equals the ratio of the two resistances in the other leg.

Question 2

What is the primary application of Y-Δ transformations?

Answer 2

Y-Δ transformations are primarily used in simplifying the analysis of three-phase power systems and complex resistor networks.

Question 3

What happens when a Wheatstone bridge is unbalanced?

Answer 3

When a Wheatstone bridge is unbalanced, current flows through the galvanometer, and the imbalance can be used to measure an unknown resistance

Question 4

What is the first step in Nodal Analysis?

Answer 4

The first step is to select a reference node (ground) and assign voltages to the other nodes relative to the reference.

Question 5

What does Mesh Analysis use to analyze circuits?

Answer 5

Mesh Analysis uses Kirchhoff’s Voltage Law (KVL) to solve for loop currents in the circuit.

Question 6

How do you apply Thevenin’s Theorem to a circuit?

Answer 6

1. Remove the load resistor. 2. Calculate the open-circuit voltage. 3. Calculate the equivalent resistance. 4. Replace the circuit with a Thevenin equivalent circuit.

Question 7

What is the Superposition Theorem?

Answer 7

It states that the voltage or current for any element in a linear circuit is the sum of the effects of each independent source acting alone.

Question 8

What is a linear circuit?

Answer 8

A circuit is linear if it obeys both the homogeneity (scaling) and additivity (superposition) properties, meaning the output is directly proportional to the input.

Question 9

State Thevenin’s Theorem.

Answer 9

Thevenin’s Theorem states that any linear circuit can be replaced by a single voltage source in series with a resistance.

Question 10

What does the Maximum Power Transfer Theorem state?

Answer 10

Maximum power is delivered to the load when the load resistance equals the Thevenin resistance of the source network.

Question 11

How do you calculate Norton’s equivalent circuit?

Answer 11

Norton’s equivalent circuit is found by calculating the short-circuit current across the terminals and the equivalent resistance when all sources are deactivated.

Question 11

What is a source transformation?

Answer 11

A method to convert a voltage source in series with a resistor into an equivalent current source in parallel with the same resistor, or vice versa.

Question 12

What are the characteristics of an ideal op-amp?

Answer 12

Infinite gain, infinite input impedance, zero output impedance, and infinite bandwidth.

Question 13

What is the gain formula for an inverting amplifier?

Question 14

What is the purpose of a voltage follower (buffer) circuit?

Answer 14

To provide high input impedance and low output impedance without amplifying the signal.

Question 15

How does a difference amplifier work?

Answer 15

It amplifies the difference between two input voltages, rejecting any common-mode signals.

Question 16

What is the primary application of a summing amplifier?

Answer 16

To sum multiple input signals, often used in audio mixing and signal processing.

Question 17

What is the formula for the energy stored in a capacitor?

Answer 17

The energy stored in a capacitor is W=12CV2W = \frac{1}{2} C V^2W=21CV2.

Question 18

What is the current-voltage relationship in a capacitor?

Answer 18

i(t)=Cdv(t)dti(t) = C \frac{dv(t)}{dt}i(t)=Cdtdv(t).

Question 19

What is the voltage-current relationship in an inductor?

Answer 19

v(t)=Ldi(t)dtv(t) = L \frac{di(t)}{dt}v(t)=Ldtdi(t).

Question 20

What is the formula for the energy stored in an inductor?

Answer 20

The energy stored in an inductor is W=12LI2W = \frac{1}{2} L I^2W=21LI2.

Question 21

What is the natural response of an RC circuit?

Answer 21

The voltage across the capacitor decays exponentially over time according to v(t)=V0e−tRCv(t) = V_0 e^{-\frac{t}{RC}}v(t)=V0e−RCt.

Question 22

What is the time constant for an RL circuit?

Answer 22

The time constant for an RL circuit is τ=LR\tau = \frac{L}{R}τ=RL.

Question 23

How does an RC circuit respond to a step input?

Answer 23

The capacitor voltage rises exponentially according to v(t)=Vs(1−e−tRC)v(t) = V_s \left( 1 - e^{-\frac{t}{RC}} \right)v(t)=Vs(1−e−RCt).

Question 24

What is the key difference in switching behavior between capacitors and inductors?

Answer 24

Capacitors resist sudden changes in voltage, while inductors resist sudden changes in current.

Question 25

What does the time constant represent in a first-order circuit?

Answer 25

The time constant represents the rate at which the circuit charges or discharges, with the response being approximately 63% complete after one time constant.

Question 26

What is the natural response of an underdamped RLC circuit?

Answer 26

The natural response of an underdamped RLC circuit includes oscillations and is of the form x(t)=Ae−αtcos⁡(ωdt+ϕ)x(t) = A e^{-\alpha t} \cos(\omega_d t + \phi)x(t)=Ae−αtcos(ωdt+ϕ).

Question 27

How is resonance frequency calculated in an RLC circuit?

Answer 27

The resonance frequency is calculated as ω0=1LC\omega_0 = \frac{1}{\sqrt{LC}}ω0=LC1.

Question 28

What is the characteristic equation for a second-order circuit?

Answer 28

The characteristic equation is d2xdt2+2αdxdt+ω02x=0\frac{d^2x}{dt^2} + 2\alpha \frac{dx}{dt} + \omega_0^2 x = 0dt2d2x+2αdtdx+ω02x=0, where α\alphaα is the damping factor and ω0\omega_0ω0 is the natural frequency.

Question 29

What is the difference between overdamped, underdamped, and critically damped circuits?

Answer 29

Overdamped circuits return to equilibrium slowly without oscillating, underdamped circuits oscillate before reaching equilibrium, and critically damped circuits return to equilibrium as quickly as possible without oscillating