When a voltage measuring device is connected to AC mains, the meter shows the steady input voltage of 220 V. This means

  1. input voltage cannot be AC voltage, but a DC voltage.
  2. maximum input voltage is 220 V.
  3. the meter reads not v but <v2>  and is calibrated to read \(\sqrt{<v^2>.}\)
  4. the pointer of the meter is stuck by some mechanical defect.

Answer (Detailed Solution Below)

Option 3 : the meter reads not v but <v2>  and is calibrated to read \(\sqrt{<v^2>.}\)

Detailed Solution

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EXPLANATION:

→When a voltage measuring device is connected to AC mains.

The meter shows the r.m.s value (Vrms) and not the peak value (V0)

Here, Vrms220 V

∴ V0 = √2× Vrms = √2×220 V ≈ 311 V

So, options (1) and (2) are incorrect. 

Again, If the input voltage is v then,

Vrms = \(\sqrt{<v^2>} \)

∴ The meter is calibrated as such to read \(\sqrt{<v^2>}\)

So, option (3) is correct and (4) is incorrect. 

So, the correct answer is option (3).

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