Download Electrical Power and Energy

Electrical Power and Energy
When a battery sends a current through a resistor, as in Fig. the battery is furnishing
energy to resistor. In effect, the battery lifts charge from the low potential at b to
higher potential at a. the potential difference between these two points is simply
the voltage of the battery. The work done by the battery in the process of lifting a
charge q from b to a is,
Let us next compute the power output of the battery as it drives a current rough
the circuit. We have known at 8th grade that
Power = W
(P)
t
P=VI
By using Ohm’s Law (V = IR) Prove that can express with
P = IRI = I2 R
P = watt (J/s)
V = volt
R = ohm
W = Joule
t = second
Q =coulomb
Factor that can influence the magnitude the power
Voltage , Resistance, Current, Time, charge
Power in electrical devices
How to calculate Energy?
R
Voltage resource
I
o
o
• Electrical Energy’s signed by E
•The unit (SI) is watt seconds
E=Pt
E= V.I.t
E = I2Rt (Because V = IR)
KWh meter, use to measure electrical Energy
Electric Stealing
CALCULATE ELECTRIC COST
Cost = Energy x tariff rate
= KWh x tariff rate (in Rupiah)
Exercises
1. In a house , there are 5 lamps of 60 watt each, a TV of 70 watt. If those electric devises are
Turned on for 4 hours every day, what is the cost that must be paid for 1 month (30 days)
If price of 1 kWh = Rp 100.00
2. A TV turned on for 10 hours per day, is connected to a voltage of 220 V and needs current
Of 3 A. If the price of 1 kWh = Rp 200.00, calculate the electricity cost that must be paid
for 1 month ( 30 day)