Electrical Circuits and Network Analysis
What the exam tests
Electrical Circuits and Network Analysis questions in MPPSC SES Electrical typically check whether you can reduce a network correctly, handle dependent sources, and interpret transient and steady-state behaviour. Accuracy in sign conventions and units matters more than lengthy manipulation.
Core rules
- KCL and KVL apply to instantaneous, phasor, and Laplace-domain quantities; state variables must be consistent.
- Superposition applies only to linear circuits and only one independent source at a time; dependent sources remain active.
- Thevenin/Norton equivalents are valid at a pair of terminals for linear networks. For dependent sources, apply a test source and find V/I.
- Maximum power transfer to a resistive load occurs at RL = Rth, giving Pmax = Vth²/(4Rth); efficiency then is 50%, not maximum efficiency.
Worked example
A 12 V independent source feeds a 4 Ω series resistor and a 6 Ω shunt resistor; the output is across the 6 Ω resistor. With the load removed, Vth = 12 × 6/(4+6) = 7.2 V. Deactivating the source gives Rth = 4 || 6 = 2.4 Ω. For maximum power, RL = 2.4 Ω and Pmax = 7.2²/(4 × 2.4) = 51.84/9.6 = 5.4 W.
Traps
Do not deactivate a dependent source; do not apply superposition to power; do not confuse Thevenin resistance with load resistance; and remember that an ideal current source has infinite internal resistance.