Alternating Current - Electromagnetism PYQ

A bulb of resistance \(280 \Omega\) is supplied with a 200 V AC supply. What is the peak current?

A resonant frequency of a current is \(f\). If the capacitance is made four times the initial value, then the resonant frequency will become

A 20 V AC is applied to a circuit consisting of a resistor and a coil with negligible resistance. If the voltage across the resistor is 12 V, the voltage across the coil is

Capacitive reactance of a capacitor in an AC circuit is \(3 \mathrm{k} \Omega\). If this capacitor is connected to a new AC source of double frequency, the capacitive reactance will become.

A coil of inductance 0.1 H and resistance \(110 \Omega\) is connected to a source of 110 V and 350 Hz . The phase difference between the voltage maximum and the current maximum is

An \(R-L-C\) circuit consists of a \(150 \Omega\) resistor, \(20 \mu \mathrm{F}\) capacitor and a 500 mH inductor connected in series with a 100 V AC supply. The angular frequency of the supply voltage is \(400 \mathrm{rad} \mathrm{s}^{-1}\). The phase angle between current and the applied voltage is

A 50 Hz AC circuit has a 10 mH inductor and a $2 \Omega$ resistor in series. The value of capacitance to be placed in series in the circuit to make the circuit power factor as unity is

The resonant frequency of an LC circuit is $f_0$. If a dielectric slab of constant 16 is inserted completely between the plates of the capacitor, then the resonant frequency is

In an LCR series circuit, if the potential differences across inductor, capacitor and resistor are $60 \mathrm{~V}, 30 \mathrm{~V}$ and 40 V respectively, then the AC voltage applied to the circuit is

A resistor of $450 \Omega$ and an inductor are connected in series to an AC source of frequency $\frac{75}{\pi} \mathrm{~Hz}$. If the power factor of the circuit is 0.6 , then the inductance connected in the circuit is

For better tuning of a series $L C R$ circuit in a communication system, the preferred combination is

In a series resonant LCR circuit, for the power dissipated to become half of the maximum power dissipated, the current amplitude is

If a resistor of resistance $4 \Omega$, a capacitor of capacitive reactance $6 \Omega$ and an inductor of inductive reactance $9 \Omega$ are connected in series with an AC source, then the impedance of the circuit is