1. Inform you about time table of exam.
2. Inform you about new question papers.
3. New video tutorials information.
- Power in Ac Circuit
- Power Factor
- Wattless Current
- Wattless current
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- Alternating current part 11 (Capacitive AC circuit)
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- Alternating current part 24 (Power in AC circuit)
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- Alternating current part 4 (Power associated with Resistors AC)
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- Alternating current part 10 (Power associated with inductor)
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- Alternating current part 8 (AC inductive circuit)
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- Alternating current part 3 (Resistive AC circuit)
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(i) An a.c. source of voltage V = V0 sin ωt is connected to a series combination of L, C and R. Use the phasor diagram to obtain expression for impedance of a circuit and the phase angle between voltage and current. Find the condition when current will be in phase with the voltage. What is the circuit in this condition called?
(ii) In a series LR circuit, XL = R and power factor of the circuit is P1. When capacitor with capacitance C such that XL = XC is put in series, the power factor becomes P2. Calculate P1/P2
Obtain an expression for average power dissipated in a purely resistive A.C. circult. Define power factor of the circuit and state its value for purely resistive A.C. circult.
Ajit had a high tension tower erected on his farm land. He kept complaining to the authorities to remove it as it was occupying a large portion of his land. His uncle, who was a teacher, explained to him the need for erecting these towers for efficient transmission of power. As Ajit realised its significance, he stopped complaining.
Answer the following questions:
(a) Why is it necessary to transport power at high voltage?
(b) A low power factor implies large power loss. Explain.
(c) Write two values each displayed by Ajit and his uncle.
(i) When an AC source is connected to an ideal inductor show that the average power supplied by the source over a complete cycle is zero.
(ii) A lamp is connected in series with an inductor and an AC source. What happens to the brightness of the lamp when the key is plugged in and an iron rod is inserted inside the inductor? Explain.