OHM’S LAW
UNDERSTANDING OHM’S LAW
• Although the three quantities, current, voltage and resistance,
are used differently, they are related to each other.
• A German physicist named George Simon Ohm (17871854) discovered this relationship and it was named in his
honor.
• The relationship is known as Ohm’s Law.
• In this law it is stated that current is directly proportional to
the voltage and inversely proportional to the resistance
IN EQUATION,
•There are devices which we can use to
measure the three quantities in a circuit.
•These three devices are the ammeter,
which measures current in amperes (or
milliamperes), the ohmmeter which
measures the resistance in ohms and the
voltmeter which measures voltage in volts.
SAMPLE PROBLEM
•How much current flows through a lamp with
resistance 90 ohms when it is connected to a
220-V outlet?
•What is the resistance of a lamp which
allows 0.8 A current when 110 V is applied
to it?
QUIZ