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Stabilization of Arc in Electric Discharge Lamps

Introduction:
Electric discharge lamps, such as fluorescent lamps, neon lamps, and sodium vapor lamps, require a stable arc for proper operation. The stabilization of the arc ensures consistent light output, prevents flickering, and prolongs the lifespan of the lamp. One common method for stabilizing the arc is by using a choke (inductor) connected in series with the supply.

Explanation:
1. Choke Connected in Series:
When a choke is connected in series with the supply in an electric discharge lamp circuit, it provides several advantages for stabilizing the arc:

- Impedance: The choke offers a high impedance to the lamp circuit, limiting the current flow and preventing excessive current surges. This helps in regulating the arc and maintaining a stable discharge.

- Inductive Reactance: The choke exhibits inductive reactance, which opposes rapid changes in current. This property helps to smooth out fluctuations in the arc current, preventing flickering and ensuring a consistent light output.

- Energy Storage: The choke stores energy in its magnetic field during the positive half-cycle of the alternating current (AC) supply. This stored energy is then released during the negative half-cycle, providing a continuous source of energy to maintain the arc in the lamp.

- Ballast Factor: The choke also acts as a ballast, which controls the power consumption of the lamp. It limits the current drawn by the lamp, ensuring that the lamp operates within its specified power rating.

2. Variable Resistance:
While a variable resistance could be used in series with the circuit to stabilize the arc, it is not a common method employed in electric discharge lamps. Variable resistance may introduce unnecessary losses and heat dissipation, which can reduce the efficiency of the lamp. Therefore, option 'B' is not the correct answer.

3. Condenser across the Supply:
Connecting a condenser (capacitor) across the supply would not stabilize the arc in an electric discharge lamp. Capacitors are commonly used in lighting circuits for power factor correction or for reducing high-frequency noise, but they do not provide the necessary characteristics for stabilizing the arc. Therefore, option 'C' is not the correct answer.

Therefore, the correct answer is option 'A', which states that a choke is connected in series with the supply to stabilize the arc in electric discharge lamps.