Power: Electrical

"rate of doing electrical work"

or

" rate of using electrical energy "

P = V * I = E / T

Power (P): Unit - Watt

Voltage (V): Unit - Volt Energy (E): Unit - Joule

Current (I): Unit - Ampere Time (T): Unit - Sec

Questions:

  1. The current flowing through an appliance connected to a 120-V source is 2 A. What is the power used by the appliance? How much energy dissipate by the appliance in one second?

  2. My battery is 9V, 250mAh. My led specification is 2V, 20mA. If I connect my led with the battery by the help of a resistor rated 350 ohm. Find out the min power rating of the resistor and the energy dissipate by the resistor in 3 h? Find out the energy dissipate by the LED in 2h?

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