Question

If we change the value of R, then

(A) Voltage does not change on L
(B) Voltage does not change on LC combination
(C) Voltage does not change on C
(D) Voltage does change on LC combination

Answer 1

Hint : Voltage provides current into the circuit as known from the Ohm’s law. The circuit of inductor, resistor and capacitor produces impedance in the circuit and impedance resists the current that is flowing through the circuit. Now, when there is change in value of voltage, the current drops too.

Complete Step By Step Answer:
According to the Ohm’s law, voltage provides current to the battery and hence the current flows through the circuit. Inductor in a circuit stores the energy produced due to the magnetic field which is produced due to the electromagnetic induction when changing current flows through the circuit. For changing current flowing through the circuit, we need an A.C. (Alternating Current) voltage source. Capacitor stores the electrical energy produced due to the accumulation of charges inside the capacitor. Also, the resistor opposes the current flowing in the circuit.
According to their impedances, the voltage provided by the AC source is distributed in the Resistor, inductor and the capacitor elements. Thus, if the value of the resistor, that is R changes, then the value of the current changes as the resistance of the resistor opposes the current flowing. Thus, the total impedance changes, which change the current flowing and according to the Ohm’s law, the voltage changes. Thus voltage changes on LC combination.
Hence option (D) is the correct answer.

Note :
The inductor and the capacitor store energy in the form of magnetic energy and electrical energy respectively, while the resistor does not store energy, it produces heat in the system due to flowing current. This heat is directly proportional to the square of the current passing through the electrical circuit.