SRM University 2007 B.Tech Electronics and Communications Engineering BANK :CIRCUIT THEORY -UNIT III - Question Paper
Wednesday, 30 January 2013 09:50Web
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PART – B
1. In the circuit shown in figure obtain the expression for the transient current and the initial rate of growth of the transient current.
2. In the circuit shown in fig. switch S is in position one for a long time and brought to position two at time t=0. Determine the circuit current.
3. Find the current in the circuit shown in fig. at an instant t, after opening the switch of a current of 1A had been passing through the circuit at the instant of opening.
4. In the circuit shown in fig. the switch initially in the position one (a) for R =100O. For the voltage across the coil the instant at which the switch is champed to position two . (b) compute the value of the R for the voltage across the coil to be decreased to 120V at the instant of switching (c) With the value of R in case(b). obtain the time take to dissipate 95% of stored energy.
5. A resistor is connected across the terminals of a 20µ.f capacitor which has been previously charged to a p.d. of 500V. If the p.d. falls to 300V in 0.5m sec. compute the resistance in mega ohms.
6. a resistance R and a 2µf capacitor are connected in series across a 200V direct supply. Across the capacitor is a neon lamp that strikes at 120V. compute R to make the lamp strike five sec after the switch has been closed. If R=5MO, how long will it take the lamp to strike.
7. Find how long it takes after the key is closed before the total current from the supply reaches 25mA, when V=10V, R =500O, R =700O and C=100µF.
8. A series RLC circuit has R=50O, L=0.2H and C=50µF. Constant voltage of 100V is impressed upon the circuit at t=0. obtain the expression for the transient current assuming initially relaxed condition.
9. A series RLC circuit with R=20O, L=10H and C=5F has a constant voltage v=-100V applied at t=0. obtain the current response in the circuit, assuming zero initial condition.
10. A series RLC circuit with R = 300O, L=1H and C=100 X 10 F has a constant voltage of 50V applied to it at t=o. obtain the maximum value of current. (Assume zero initial condition)
11. A series RLC circuit with R=5O , L=0.1H and C = 500 X 10 F has a DC voltage of 100V applied at t=0 through a switch. obtain the resulting current transients.
12. A step voltage V(t) = 100a(t) is applied to a series RLC circuit with L=10H.R=2O and C=5F. The initial current in the circuit is zero but there is an initial voltage of 50V on the capacitor in a direction which opposes the applied source. obtain the expression for the current in the circuit.
13. For a source free RLC series circuit, the initial voltage across C is 10V and the initial current through L is zero. If L=20mH, c=0.5µf and R = 100O. Evaluate i(f)
14. For the circuit shown in fig. obtain the voltage across the resistor 0.5O when the switch, S, is opened at t=0. presume that there is no charge on the capacitor and no current in the inductor before switching.
15. In the circuit shown in fig. obtain the current ‘i’. presume that initial charge across the capacitor is zero.
16. In the series RL circuit shown in fig. the applied voltage is e=100e . obtain (a) resulting current (b) Initial rate of change of current.
17. An exponential voltage v(t) = 5e is applied at time t=0 to a series RC circuit comprising of R=5O and C=0.1F. find the complete particular solution for current i(t) through the capacitor. presume zero charge across ‘C’ before application of driving voltage.
18. In the circuit shown in fig. the switch is closed at time t=o. find i(t). presume zero current through inductor L and zero charge across C before closing the switch.
19. For the circuit shown in fig. determine the currents i and i when the switch is closed at t=0. presume that the initial current through the inductor is 0
20. In the fig. shown V(t) = 10volts. obtain i (t) presume all initial conditions to be zero. Use Lap lace transformer technique.
| Earning: Approval pending. |
