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NEET2016PhysicsCurrent ElectricityActual

A filament bulb ( 500   W ,   100   V ) is to be used in a 230   V main supply. When a resistance, R is connected in series, it works perfectly and the bulb consumes 500   W . The value of R is

Options

  1. A230 Ω
  2. B46 Ω
  3. C26 Ω
  4. D13 Ω

Correct answer

C. 26 Ω

Step-by-step solution

In the series, the current is the same in the bulb and the extra resistance, which is given by, I = P V = 500 100 = 5   A . But, V bulb + V R = V net . So, voltage across resistance R will be, V R = V net - V bulb ⇒ V R = 230 - 100 = 130   V . From Ohm's law, R = V R I = 130 5 = 26   Ω .

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