A 12 V source is connected across a 10 Ω resistor. How much energy is used in two minutes? The book states its .480 Wh, how is this figured and put into a formulae?
2007-09-02 12:38:45 · 4 answers · asked by Chris 2 in Science & Mathematics ➔ Engineering
There are two laws to look at. Ohms law and watts law.
Ohms law: E = R * I
Watts law: P = E * I
Where E is voltage, I is current in amps, P is power in watts and R is resistance in ohms. We need I to find power so we convert ohms law to (I = E/R) by dividing both sides by R. Insert numbers.
I =12v / 10 ohms = 1.2 amps
Now we want to find the power in watts P so we use watts law.
P = 12v * 1.2amps = 14.4 watts
To get watt hours, we multiply the watts times the time in hours to get watt hours. One hours is 60 minutes, two minutes is 1/30 of an hour.
14.4 watts * (1/30) hours = 0.480 watt hours
2007-09-02 12:53:10 · answer #1 · answered by Anonymous · 1⤊ 0⤋
The wattage is E squared/R. That gives (12)(12)/10 = 14.4 watts. Since 2 minutes is 2/60 hours the watt hours is 14.4*2/60, which =.48
So when you do the arithmetic you get .48Watt hrs.
2007-09-02 15:45:22 · answer #2 · answered by Rich Z 7 · 0⤊ 0⤋
Power is V^2/R
144 v/10 Ohm= 14.4 watts
2 mins is 0,0333 hours
14.4*0.0333= .48 W-h
2007-09-02 12:57:49 · answer #3 · answered by Bernie 2 · 0⤊ 0⤋
14.4 watts. Time makes no difference. I = E divided by R (12 divided by 10) equals 1.2 amps P= I squared X R 1.2 squared (1.44) X R = 1.44X10 equals 14.4 watts
2016-05-19 21:49:09 · answer #4 · answered by ? 3 · 0⤊ 0⤋