Network Theory

Q:   A connection is made consisting of resistance A in series with a parallel combination of resistances B and C. Three resistors of value 10Ω, 5Ω, 2Ω are provided. Consider all possible permutations of the given resistors into the positions A, B, C, and identify the configurations with maximum possible overall resistance, and also the ones with minimum possible overall resistance. The ratio of maximum to minimum values of the resistances (up to second decimal place) is ____________.

Q:   In the given circuit, the values of V1 and V2 respectively are

• A:  5V, 10V
• B:  10V, 30V
• C:  15V, 35V
• D:  0V, 20V

Q:   Consider a delta connection of resistors and its equivalent star connection as shown below. If all elements of the delta connection are scaled by a factor k , k > 0 , the elements of the corresponding star equivalent will be scaled by a factor of

• A:  k²
• B:  k
• C:  1/k
• D:  k^1/2

Q:   A source vs(t) = Vcos 100Πt has an internal impedance of (4 + j3)Ω. If a purely resistive load connected to this source has to extract the maximum power out of the source, its value in W should be

• A:  3
• B:  4
• C:  5
• D:  7

Q:   Two magnetically uncoupled inductive coils have Q factors q1 and q2 at the chosen operating frequency. Their respective resistances are R1 and R2. When connected in series, their effective Q factor at the same operating frequency is

• A:  q1 + q2
• B:  (1/q1) + (1/q2)
• C:  (q1.R1 + q2.R2)/(R1+ R2)
• D:  (q1.R2+ q2.R1)/(R1+ R2)

Q:   The average power delivered to an impedance (4 - j3)W by a current 5 cos (100pt + 100)A is

• A:  44.2W
• B:  50W
• C:  62.5W
• D:  125W

Q:   In the circuit shown below, the initial charge on the capacitor is 2.5 mC, with the voltage polarity as indicated. The switch is closed at time t = 0. The current i (t) at a time t after the switch is closed is

Q:   For parallel RLC circuit, which one of the following statements is NOT correct ?

• A:  The bandwidth of the circuit decreases if R is increased
• B:  The bandwidth of the circuit remains same if L is increased
• C:  At resonance, input impedance is a real quantity
• D:  At resonance, the magnitude of input impedance attains its minimum value.

Q:   A fully charged mobile phone with a 12 V battery is good for a 10 minute talktime. Assume that, during the talk-time the battery delivers a constant current of 2 A and its voltage drops linearly from 12 V to 10 V as shown in the figure. How much energy does the battery deliver during this talk-time?

Q:   The first and the last critical frequency of an RC -driving point impedance function must respectively be

• A:  a zero and a pole
• B:  a zero and a zero
• C:  a pole and a pole
• D:  a pole and a zero