1. Objective 16.02 Compute electrical energy and cost

2. Formulas to compute electrical energy and cost Watts = volts x amps –W=VA How many watts of electricity will a 7.5 amperes electric motor use in 5 hours on a 120 volt circuit? –W=VAT –W=(120)(7.5)(5) –W=4500 watts

3. Formulas to compute electrical energy and cost Volts = watts / amps. V = W/A What volt circuit is needed for a 7.5 amp electric motor that uses 900 watts in 1 hour? –V = 900/7.5 (1) –V = 120

4. Formulas to compute electrical energy and cost Amps equal watts divided by volts A = W/V What should the amp rating of an electric motor be if it uses 900 watts of electricity in 1 hour in a 120 volt circuit? –A = 900/120 (1) –A = 7.5 amps

5. Formulas to compute electrical energy and cost Ohms Law I = E/R –I = amps –E = volts –R = resistance

6. Cost of electricity Cost of electricity = cost/kwh x number of kw x hours of use If electricity costs 12 cents/kwh, how much would it cost to use 2 kw/hr for 10 hours? –.12x2x10 = $2.40