Advertisements
Advertisements
Question
Transformers are used ______.
Options
in DC circuits only
in AC circuits only
in both DC and AC circuits
neither in DC nor in AC circuits
Solution
Transformers are used in AC circuits only.
Explanation:
When a DC supply is provided to a transformer, there will be no change in flux with time across the coils of the transformer. So, there will be no induced emf in the secondary coil due to changing current in the primary coil. Hence, the transformer cannot operate in DC because of the violation of its working principle.
APPEARS IN
RELATED QUESTIONS
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 the expression for an 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?
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.
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
Prove theoretically the relation between e.m.f. induced in a coil and rate of change of magnetic flux in electromagnetic induction.
The power factor of an a.c. circuit is 0.5. What is the phase difference between voltage and current in this circuit ?
A series AC circuit has a resistance of 4 Ω and a reactance of 3 Ω. The impedance of the circuit is
An electric bulb is designed to consume 55 W when operated at 110 volts. It is connected to a 220 V, 50 Hz line through a choke coil in series. What should be the inductance of the coil for which the bulb gets correct voltage?
Consider the situation of the previous problem. Find the average electric field energy stored in the capacitor and the average magnetic field energy stored in the coil.
Following figure shows a typical circuit for a low-pass filter. An AC input Vi = 10 mV is applied at the left end and the output V0 is received at the right end. Find the output voltage for ν = 10 k Hz, 1.0 MHz and 10.0 MHz. Note that as the frequency is increased the output decreases and, hence, the name low-pass filter.
An ac circuit as shown in the figure has an inductor of inductance L and a resistor of resistance R connected in series. Using the phasor diagram, explain why the voltage in the circuit will lead the current in phase.
Answer the following question.
Show that an ideal inductor does not dissipate power in an ac circuit.
The power factor in a circuit connected to an A.C. The value of power factor is ______.
Which of the following quantities remains constant in a step-down Transformer?
The power factor of an a.c circuit having resistance R and inductance L Connected in series to an a.c source of angular frequency co is.
In an AC. circuit, the current is :
i = `5 sin (100t - pi/2)` amp.
and the a.c. potentiol is:
V = 200 sin (100t) volt.
Then the power consumption is
In the series LCR circuit, the power dissipation is through ______
An alternating current generator has an internal resistance Rg and an internal reactance Xg. It is used to supply power to a passive load consisting of a resistance Rg and a reactance XL. For maximum power to be delivered from the generator to the load, the value of XL is equal to ______.
An alternating current I = 14 sin (100 πt) A passes through a series combination of a resistor of 30 Ω and an inductor of `(2/(5pi))` H. Taking `sqrt2` = 1.4 calculate the power factor of the circuit.
