Respuesta :
In Europe, the standard voltage in homes is 240 V and in the United States, it is 120 V.
(a) If you bring a “200-W” European bulb home to the United States, what should be its U.S. power rating?
Recall that the power of a bulb is given by
[tex]P=VI[/tex]Where V is the voltage and I is the current.
In Europe, the current flowing through a 200 W bulb is
[tex]I=\frac{P}{V}=\frac{200}{240}=0.833\; A[/tex]So, a current of 0.833 A will be flowing through the bulb in Europe.
The equivalent power rating of the bulb in the United States is
[tex]P=VI=120\cdot0.833=100\; W[/tex]So, the equivalent power rating of the bulb should be approximately 100 W.
(b) How much current will the “200-W” European bulb draw in normal use in the United States?
The rating of the bulb is 200 W and the voltage in the United States is 120 V
So, the current drawn by the bulb is given by
[tex]I=\frac{P}{V}=\frac{200}{120}=1.667\; A[/tex]As you can see, the bulb will draw more current if the voltage is reduced to supply the same power.
Therefore, the bulb will draw a current of 1.667 A
