When a lamp is connected to an alternating voltage supply, it lights with the same brightness as when connected to a 12 V d.c. battery. what is the peak value of alternating voltage source?

When the lamp connected to an alternating voltage supply lights with the same brightness as when connected to a 12 V DC battery, the RMS value of the AC voltage is 12 V. The peak value (V peak ) is √2 × 12 ≈ 16.97V.

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