A lamp is rated at 12V,6W. What does this mean? How much current is passing through the lamp when it is connected to a 12v supply?

Expert Answers
gsenviro eNotes educator| Certified Educator

V (stands for volt) is the units for voltage and W (stands for watts) is the unit of power. A lamp that is rated as 12 V, 6 W will draw 6 W of power when connected at 12 V supply. The lamp will work most efficiently at 12 V supply. If connected across a higher voltage, it may get damaged or may have lesser life. If connected across a lower voltage, it will provide lesser brightness.

Power, voltage and current are related by the following expression:

P = V x I

where, P is the power, V is the voltage and I is the current.

In this case, P = 6 W and V = 12 V

thus, I = P / V = 6 W / 12 V = 0.5 A or 500 mA

Thus, a current of 0.5 A or 500 mA will pass through the lamp when it is connected to a supply of 12 V.

Hope this helps.