• A charge q gains an energy qV moving through a potential V supplied by a battery. This energy must be dissipated by collisions of the charge in the circuit or else the charge would accelerate in response to the voltage across the wire.
  
  
• The rate at which energy (work in this case) is converted into heat is equal to the power P dissipated in the circuit.

SI: Watt = W = Amp.Volt = J/s

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Alternate forms of Joule's Law for Ohmic Materials: V = I R

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Electrical Shock Hazard for 120 V Circuits*

Current	Power	Effect
1 mA	0.12 W	Mild Shock
10 mA	1.2 W	Paralysis of Motor Muscles
20 mA	2.4 W	Paralysis of Chest Muscles (Breathing Stops) Death in few minutes
100 mA	12 . W	Ventricular Fibrillation (Heart Arrested) Death in few seconds
1000 mA	120. W	Sever Burns Death instantly

* Dependent upon a variety of conditions including the current path.

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