Electricity is defined. Electric current is the movement of charged particles in a specific direction. Current, charge, and time are related by the equation current = charge / time. Voltage is known as electromotive force or potential difference and is the electric pressure that causes current to flow. Voltage, charge, and energy are related by the equation voltage = energy / charge. Resistance is the opposition a material offers to current. Ohm's Law states that current is directly proportional to voltage and inversely proportional to resistance, represented by the equation I=V/R. Sample problems demonstrate calculating current, voltage, and resistance using Ohm's Law.

1. ELECTRCITY

2. ELECTRIC CURRENT
• Is the movement of charged particles in a specific direction.
• The relationship between time, charge and current is given as :
current = charge / time
I = q / t
The unit is
ampere = coulomb / second
A = C / s

3. VOLTAGE
• Is known as electromotive force or potential difference. It is the
electric pressure that causes current to flow.
• The relationship between charge, energy and voltage is
voltage = energy / charge or
V= W / q
The unit is
volt = joule / coulomb or
V= J/ C

4. RESISTANCE
•Is the opposition a material offers
current.
•The symbol for resistance is R.

5. OHM’S LAW
• It is named by the German physicist Georg Simon Ohm
(1787 – 1854 )
• It is stated as ; current is directly proportional to the
voltage and inversely proportional to the resistance.
• Equation form:
• I= V/R
• From this equation, V = IR and R = V/I

6. SAMPLE PROBLEMS
• 1. How much current flows through a lamp with resistance 90 –
ohm when it is connected to a 220-V outlet?
• 2. What is the drop in voltage from the generator to the
auditorium when a current of 15 A is used and the resistance of
the wires is 0.3 – ohm?
• 3. What is the resistance of a lamp which allows 0.8 A current
when 110.0 V is applied to it?

7. SAMPLE PROBLEMS
• 1. How much current flows through a lamp with resistance 90 –
ohm when it is connected to a 220-V outlet?
• 2. What is the drop in voltage from the generator to the
auditorium when a current of 15 A is used and the resistance of
the wires is 0.3 – ohm?
• 3. What is the resistance of a lamp which allows 0.8 A current
when 110.0 V is applied to it?