Yes, Determine Current From Watts

[gkangelexa]

Can you determine current given only the watts?

Ex) if you have a lightbulb with 120 Watts, can you determine the current (charge) that flows through it in a second, for example?

 

[sophiecentaur]

Nope.
In a low voltage circuit, you need a lot of current to produce the same power as for a high voltage circuit.
Remember - Power (Watts) = Volts (Volts) X Current (Amps)

 

[potatoecannon]

From the way the question is phrased, no was the correct answer.
You need any 2 (Voltage/Current/Resistance/Power) to determine an unknown in basic circuits.

However, if you MEANT (since you referenced a 120W light bulb) how much current will the bulb draw on a standard 120 VAC circuit, then that is simply P=V*I ---> I = P/V = 120W/120V = 1 Amp.

A 120 W rated bulb will not actually draw/dissipate 120 W of power unless it is powered by the expected voltage (ie a 12V battery will not push 10 amps through it).

 

[jambaugh]

Can you determine current given only the watts?

Ex) if you have a lightbulb with 120 Watts, can you determine the current (charge) that flows through it in a second, for example?

In general no, you need also voltage:
Power = voltage times current.

In the lightbulb example you probably know the voltage implicitly i.e. it's a lightbulb used with 120V AC house lights. In that case you would solve to find the current is 1 amp (1 coulomb per second).

current = power / voltage

 

[sardar]

I can say that it is possible to determine the current from watts, but it would require additional information. Watts is a unit of power, which is the rate at which energy is transferred or used. Current, on the other hand, is a measure of the flow of electric charge. In order to determine the current from watts, we would need to know the voltage of the circuit as well. This is because the formula for power (watts) is P = IV, where I is the current and V is the voltage. Therefore, with the knowledge of both watts and voltage, we can calculate the current using the formula I = P/V. In the example given, if we know the voltage of the circuit, we can determine the current flowing through the lightbulb with 120 watts of power. However, if we do not have the voltage information, we cannot accurately determine the current from watts alone.