This document discusses electric circuits and Ohm's law. It defines Ohm's law as stating that the current through a conductor is directly proportional to the voltage applied, provided the temperature remains constant. It also differentiates between ohmic conductors, whose resistance remains constant, and non-ohmic conductors, whose resistance changes. Graphs and equations are provided showing the relationships between current, voltage and resistance as defined by Ohm's law.

1. ELECTRIC CURCUITS

2. Lesson Objectives
• State Ohm’s Law
• Interpret graphs on the
relationships between current,
voltage and resistance
• Differentiate between ohmic and
non ohmic conductors
In this
lesson
we will:

3. Lesson Introduction
Electrical circuits are everywhere in our lives, from very complex ones that
control computers and smart phones, to the simpler circuits that allow you
to switch a lightbulb on and off.
In order to understand how circuits work, we must understand Ohm’s law,
which explains the relationships between the key concepts in a circuit.

4. Ohm’s Law
• It is the relationship between voltage, current and resistance

5. Ohm’s Law
states:
• For a conductor at a constant temperature, the
current in the conductor is directly proportional
to the voltage (potential difference) across it.

6. Ohm’s Law Triangle
Depending on which variable you are trying to solve for, you can manipulate the
equation.

7. Ohm’s Law
• We can also use a graph to show
the relationship as stated by
Ohm’s law.
• If a conductor obeys Ohm’s Law,
its resistance remains constant
provided that its temperature
remains constant also.
• At a constant temperature, the
ratio of V/I remains constant.

8. Ohmic vs. Non-ohmic conductors
Ohmic conductor: Obeys Ohm’s Law
• Its resistance remains constant provided its
temperature does not change
• Current directly proportional to voltage
Non-ohmic conductor: DOES NOT obey Ohm’s Law
• Its resistance does not remain constant
• Current is not directly proportional to voltage

9. Ohmic vs. Non-ohmic conductors
Ohmic: Any increase in voltage creates a
linear increase in current
Non-ohmic: Any increase in voltage creates
a bon linear increase in current. Resistance
changes based on current moving on it.

10. Questions
1. A load has a 1.2 A current flowing through it. The voltage across the
load is 6.0 V. What is the resistance of the load?
2. What happens to current (I) when the voltage (V) is increased in a
circuit?
3. What happens to current (I) when the resistance (R) is increased in
a circuit?