List of top Physics Questions on Alternating current asked in AIIMS

A transformer with efficiency 80% works at $4\, kW$ and $100\, V$. If the secondary voltage is $200\,V$, then the primary and secondary currents are respectively

In an LCR circuit as shown in figure, both switches are open initially. Now switch S is closed, S kept open. (q is charge on the capacitor and $\tau$ = RC is capacitive time constant). Which of the following statement is correct?

At resonance, $LCR$ series circuit have a minimum current. At resonance, in $LCR$ series circuit, the current and e.m.f are not in phase with each other

The most suitable metal for making electromagnets and transformer cores is

Find the voltage drop across a capacitor connected with a resistance and a battery of $60\, V$ in series after a long time.

A transmitter transmits at a wavelength of $300\, m$. A condenser of capacitance $2.4\, \mu F$ is being used. The value of the inductance for the resonant circuit is approximately

An AC ammeter is used to measure current in a circuit. When a given direct current passes through the circuit, the AC ammeter reads 3 A. When another alternating current passes through the circuit, the AC ammeter reads 4 A. Then the reading of this ammeter, if DC and AC flow through the circuit simultaneously, is

The core of any transformer is laminated so as to

Transformers are used only in alternating current source not in direct current. Only a.c. can be stepped up or down by means of transformers.

: The alternating current lags behind the e.m.f. by a phase angle of $\pi / 2$, when AC flows through an inductor. : The inductive reactance increases as the frequency of $A C$ source decreases.

A $50\, Hz$ AC source of $20$ volts is connected across $R$ and $C$ as shown in figure. The voltage across $R$ is $12$ volt. The voltage across $C$ is

In an ideal parallel $LC$ circuit, the capacitor is charged by connecting it to a $DC$ source which is then disconnected. The current in the circuit

Which of the following quantity is increased in a step-down transformer?

In series LCR circuit, the resonance occurs at one frequency only. At resonance the inductive reactance is equal and opposite to the capacitive reactance.

In an A.C.circuit containing only capacitance, the current