AC Circuits
AC Circuits
- In a series LCR circuit, \(L=\frac{1}{\pi}\) H and \(C=\frac{1}{\pi}\) μF. The resonant frequency is Answer: A. 500 Hz f=1/2π√(LC)=frac12π·frac10⁻³π=500 Hz. 1
- In a series RL circuit, R = 30 Ω and \(X_L\) = 40 Ω. The power factor of the circuit is Answer: D. 0.6 Z=√(30²+40²)=50\ Ω , cosφ=R/Z=0.6 . 1
- A 100 µF capacitor is charged with a 50 V source supply. Then source supply is removed and the capacitor Data: C = 100 µF = 100 × 10⁻⁶ F = 10⁻⁴ F, V = 50V, i = 5A The energy stored in the electric field in the capacitor = 1/2 CV² The energy stor... 1
- Compare resistance and reactance. Resistance Reactance It is a property of a material or component that opposes the flow of current through it. It is a property of a material... 1
- What is the natural frequency of L C circuit ? What is the reactance of this circuit at this frequency The natural frequency of LC circuit is 1/2 π √(L C) , where L is the inductance and C is the capacitance. The reactance of this circuit at t... 2
- What is wattless current ? The current that does not lead to energy consumption, hence zero power consumption, is called wattless current. In the case of a purely indu... 1
- For very high frequency AC supply, a capacitor behaves like a pure conductor. Why ? The reactance of a capacitor is XC = 1/2 π f C , where f is the frequency of the AC supply and C is the capacitance of the capacitor. For ve... 1
- The total impedance of a circuit decreases when a capacitor is added in series with L and R. Explain why ? For an LR circuit, the impedance, Z_LR = sqrtR²+X_L² , where X_L is the reactance of the inductor. When a capacitor of capacitance C is adde... 1
- An electric lamp is connected in series with a capacitor and an AC source is glowing with a certain brightness. Answer: The lamp glows more brightly when the capacitance is increased. For the lamp (resistance R) in series with a capacitor C on an AC su... 1