Question

A 12-V DC automobile head lamp is to be used on a fishing boat with a 24-V power system. The head lamp is rated at 50 W. A resistor is to be connected in series with the lamp to permit it to operate on 24 V. What should be the resistance and power rating of the resistor?

Answer 1

Answer:

The  resistance is  $R = 2.88 \ \Omega$

Explanation:

From the question we are told that

    The  voltage  rating of the headlamp is  $V_1 = 12 \ V$

     The  voltage of the power system is  $p = 24 \ V$

     The  power rating of the headlamp  is  $P = 50 W$

Generally the power which the resistor dissipates is mathematically represented as

      $P = V_L * I$

=>       $50 = 12 * I$

=>   $I = 4.1667 \ A$

Generally the resistance is

      $R = \frac{V_1 }{I}$

      $R = \frac{12 }{4.1667}$

      $R = 2.88 \ \Omega$