When you walk through a metal detector carrying a metal object in your pocket,it raises an alarm. This phenomenon works on

Power delivered by the source of the circuit becomes maximum,when

An alternating current is flowing through a series $L-C-R$ circuit. It is found that the current reaches a value of $1 \ mA$ at both $200 \ Hz$ and $800 \ Hz$ frequency. What is the resonance frequency of the circuit (in $Hz$)?

$A$ series $LCR$ circuit is connected to an alternating source of emf $E$. The current amplitude at resonant frequency is $I_0$. If the value of resistance $R$ becomes twice of its initial value,then the amplitude of current at resonance will be

When resonance is produced in a series $LCR$ circuit,then which of the following is not correct?

$A$ series $LCR$ circuit is connected to an ac voltage source. When $L$ is removed from the circuit,the phase difference between current and voltage is $\frac{\pi}{3}$. If instead $C$ is removed from the circuit,the phase difference is again $\frac{\pi}{3}$ between current and voltage. The power factor of the circuit is: