Download Calculating Electricity

Calculating Electricity
Ohm’s Law and Power Equation
Ohm’s Law
Relationship between voltage,
current, and resistance
Ohm’s Law
E
represent voltage, (E is short for
electromotive force)
 I represent current measured in
amperes
 R represent resistance measured in
ohms
Ohm’s Law
 Relationship
between E, I, and R
E=IxR
Ohm’s Law
 Assume
that 10 A of current flows in
circuit having a total resistance of
11 ohms. What is the source
voltage?
E=IxR
Ohm’s Law
 Using
the formula
E=IxR
E= 10 A x 11ohms
E = 110 volts
Ohm’s Law
 Assume
that there are 6 amps of
current flowing through a 120 volt
circuit. What is the resistance?
R=E÷I
Ohm’s Law
 Using
the formula
R=E÷I
R = 120 volts ÷ 6 amps
R= 20 ohms
Ohm’s Law
 Assume
that you need to know how
much current is flowing through a
115 volt circuit containing 25 ohms
of resistance. What is the amperage
of the circuit?
I=E÷R
Ohm’s Law
 Using
the formula
I=E÷R
I = 115 volts ÷ 25 ohms
I = 4.6 amps
Power Equation
Relationship between watts,
amps, and volts
Power Equation



P for watts (P represents power)
I for amps
E for volts
Power Equation

Relationship between P, I, and E
P=IxE
Power Equation
 Assume
that .83 amps of current
flows through 120 volt circuit. How
many watts of electrical power are
being used?
P=IxE
Power Equation
 Using
the formula
P=IxE
P = .83 amps x 120 volts
P = 99.6 watts of power
Power Equation
 Assume
that there are 5, 100 watt
light bulbs being operated on a 115
volt circuit. How many amps of
current are flowing through the
circuit?
I=P÷E
Power Equation
 Using
the formula
I=P÷E
I = 500 watts ÷ 115 volts
I = 4.35 amps of current
Power Equation
 Assume
that there is a 1200 watt
coffee pot pulling 10 amps. What is
the source of voltage?
E=P÷I
Power Equation
 Using
the formula
E=P÷I
E = 1200 watts ÷ 10 amps
E = 120 volts