LED Power Rating on information on my 12v lamp

[EddieB]

On the LED lamp I have I have the following information, 12v-440mA-3.4W, these figures don't stack up according to Ohms Law, I'm not too familiar with load ratings and calcs regarding LED's

 

[Lucien Nunes]

The LED chip itself may be 3.4W but the power used from the circuit is higher due to the loss in the ballast resistors. Same as with fluorescents and discharge lamps, where e.g. a 36W fitting takes a 36W tube but uses more than 36W from the mains due to loss in the control gear.

BTW ohn's law is about resistance not power.

 

[EddieB]

The LED chip itself may be 3.4W but the power used from the circuit is higher due to the loss in the ballast resistors. Same as with fluorescents and discharge lamps, where e.g. a 36W fitting takes a 36W tube but uses more than 36W from the mains due to loss in the control gear.

BTW ohn's law is about resistance not power.

Thank you for your reply, it makes sense but your statement about ohms law confuses me, power, voltage, resistance and current can all be obtained with any two readings ..

 

[Lucien Nunes]

Yes, but ohm's law only states that the current through a conductor is proportional to the voltage across it (for most materials.) Ohm's law doesn't apply to LEDs since they are semiconductors and do not have a linear relationship between current and voltage. But the power is still voltage multiplied by current, as that relationship doesn't depend on ohm's law.

 

[EddieB]

Yes, but ohm's law only states that the current through a conductor is proportional to the voltage across it (for most materials.) Ohm's law doesn't apply to LEDs since they are semiconductors and do not have a linear relationship between current and voltage. But the power is still voltage multiplied by current, as that relationship doesn't depend on ohm's law.

Thanks for clearing that one up