Solved Anna University Question Paper with Answer - 2 (PART A)

Question Paper Code: 80124

B.E./B.Tech. DEGREE EXAMINATIONS, APRIL/MAY 2019.

Second Semester

Electrical and Electronics Engineering

EE 8251-CIRCUIT THEORY

(Common to Electronics and Instrumentation Engineering/B.E. Instrumentation and Con troll Engineering)

(Regulation 2017)

Time: Three hours Maximum: 100 Marks

Answer ALL questions.

PART A-(10 x 2 = 20 Marks)

1. State Kirchoff's Current law.

 It states that "the algebraic sum of the current meeting at a junction (node) is equal to zero".

2. Find the equivalent resistance of circuit with three resistors connected in series each having a resistance value of 3 Ohms.

R_eq = R₁ + R₂ + R₃

R_eq =3 + 3 + 3

Req = 9Ω

3. What is the condition for maximum power transfer in DC circuits?

P_max = V² / 4 RL

Maximum power win be delivered from a voltage source to load, when load resistance is equal to internal resistance of the source.

4. Sate Thevenin's theorem.

Any liner active network with output terminals can be replaced by a single voltage (V_th) in series with a single impedance (R_th).

5.Write down the time constant of RL and RC circuit.

Time constant of RL

T = I (1- e^-1)

T = 63.2% of I

Time constant of RC T = 0.368 × I

6. How does an inductor act at t = 0⁺ and t = a?

t = 0

7. Define Quality factor.

It is the ratio of f₀, to (f₂-f₁) is called quality factor of a coil. It is represented by Q

Q =f₀ / f₂ - f_i (or) 1/R √ L/C

8. Find the current through the circuit with 5 Ohms resistor across a voltage source of 10cos(50t - 50°) Volts.

9. Mention the expression for resonant frequency in series resonance.

f₀=  1/ 2π √ LC

10. Define coefficient of coupling.

Coefficient of coupling is defined is defined as ratio of mutual inductance to the geometric mean of the self inductance

K = M / √√L₁ L₂