Exams › JEE Main › Physics

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Choke coil is simply a coil having a large inductance but a small resistance. Choke coils are used with fluorescent mercury-tube fittings. If household electric power is directly connected to a mercury tube, the tube will be damaged. Reason (R) : By using the choke coil, the voltage across the tube is reduced by a factor (R / √(R² + ω²L²)), where ω is frequency of the supply across resistor R and inductor L. If the choke coil were not used, the voltage across the resistor would be the same as the applied voltage. In the light of the above statements, choose the most appropriate answer from the options given below :

1. Both (A) and (R) are true but (R) is not the correct explanation of (A).
2. (A) is false but (R) is true.
3. Both (A) and (R) are true and (R) is the correct explanation of (A).
4. (A) is true but (R) is false.

Correct answer: Both (A) and (R) are true and (R) is the correct explanation of (A).

Solution

Both statements accurately describe the function of a choke coil in fluorescent lighting systems. The assertion correctly identifies the role of the choke coil in preventing damage to the mercury tube by limiting the current, while the reason explains the mechanism by which the choke coil reduces the voltage across the tube, thus supporting the assertion.

Related JEE Main Physics questions

• An AC source of angular frequency $\omega$ is connected across a series combination of a resistor $r$ and a capacitor $C$. The circuit current is $I$. If the source frequency is reduced to $\omega/3$ while the applied voltage amplitude remains unchanged, the current becomes $I/2$. The ratio of capacitive reactance to resistance at the original frequency $\omega$ is
• A series LCR circuit has a resistor of 200 \(\Omega\) and is connected to a 220 V, 50 Hz AC supply. If the capacitor is removed first and then the inductor is removed, the voltage across the resistor in the circuit is found to lead the supply voltage by 30\(^\circ\). Also, when the inductor is removed, the current is observed to lead the voltage by 30\(^\circ\). The power dissipated in the circuit is
• A radio receiver's tuned circuit contains a 50 \(\Omega\) resistance, a 10 mH inductor, and a variable capacitor. If a 1 MHz radio signal induces a potential difference of 0.1 mV, the capacitor value required for resonance is
• In a circuit, the instantaneous current and voltage are expressed by \[ i=\frac{1}{\sqrt{2}}\sin(100\pi t)\,\text{A},\qquad e=\frac{1}{\sqrt{2}}\sin(100\pi t+\pi/3)\,\text{V} \] What is the average power, in watts, dissipated in the circuit?
• In a series L-C circuit, the current reaches its peak when the inductance is 0.5 H and the capacitance is 8 \(\mu\text{F}\). What is the angular frequency of the applied alternating voltage?
• A coil has a resistance of 30 a9 and an inductive reactance of 20 a9 at a frequency of 50 Hz. If a 200 V AC supply of frequency 100 Hz is applied across the coil, the current through it will be

⚔️ Practice JEE Main Physics free + battle 1v1 →