ELECTRIC POWER AND ELECTRICAL ENERGY USE BY CONSUMERS Power source The power source is the work done per unit time an electric current, or electrical energy used a power tool (a modified atom per unit time). At every tool lsitrik always listed the amount of electrical power tools. For example, on a 60 W incandescent written / 220 V, meaning that when the lights are installed on the voltage 220 volts, will produce electric power of 60 W Based on the above definition, the power can be expressed as follows. P=W/t Description: P = power (watts) W = energy (joules) t = time (second) Since V = I x R, electrical power can also be expressed as follows P = V x I or P = I2 x R or P = V2 / R V = potential difference (volts) I = strong electric current (amperes) R = resistance (ohms) Example question A power tool reads 220 V and 1.5 A. What is the power of these tools? If the tool is used for 60 minutes, how much energy is used? Completion Given: V = 220 volts I = 1.5 amperes t = 60 min = 3600 second asked: a) P and b) W said: a) P = V x I P = 220 x 1.5 = 330 watts b) W = P x t W = 330 x 3600 = 1,188,000 joules = 1188 kilojoules Greater energy unit commonly used in the short kilowatthour (kWh). 1 kWh = 3. 600,000 joules. In Indonesia the daily life of the state electricity company calculates electrical energy used by consumers using the kWh meter. Unit of electrical energy used is expressed in units of electricity meters. Example question A subscription to the electricity use of power tools, such as incandescent lamps of 25 watts each 4 pieces that light up an average of 10 hours per day, turned on the TV 80 watts average of 6 hours per day, and 300 watt electric iron used an average of 1 hour per day. What is the subscription price to be paid one month (30 hari) if every electric meter costs Rp. 500? Completion Given: 4 lamps of 25 watts, t = 10 hours / day 1 TV 80 watts, t = 6 hours / day 1 board 300 watts, t = 1 hour / day Asked: subscription price of electricity a month? Answer: Stage 1: The electrical energy used in watt hours W1 = 4 x 25 W x 10 hours = 1000 Wh W2 = 1 x 80 W x 6 hours = 480 Wh W3 = 1 x 300 W x 1 hour = 300 Wh The electrical energy all the tools = W1 + W2 + W3 = 1000 + 480 + 300 = 1,780 Wh Stage 2: The electrical energy used in 1 month W = 1780 x 30 days = 53.400 Wh = 53.4 kWh Stage 3: The total cost of electricity in 1 month Total cost = 53.4 x Rp. 500 = Rp. 26,500 So a little explanation about power and calculate the electrical energy used in everyday life.