# Ohm’s Law

Created 3 years ago

Duration 0:06:28
231
Slide Content
1. ### Slide 1 - Ohm’s Law

• Voltage, Current & Resistance
2. ### Slide 2 - Current

• An electrical current is the flow of electrons through a complete circuit.
• The brightness of a light bulb is an indicator of the amount of current (or flow) through the bulb.
• The unit of current is the Ampere (A) or “amp” for short.
3. ### Slide 3 - The amount of current that flows in a circuit depends on the resistance of the circuit and the voltage of the source.

• * In other words, a battery does not supply a constant amount of current.
• Current is Variable
4. ### Slide 4 - Voltage

• Voltage is the push that drives flow of electrons.
• Voltage in a circuit is determines by the source
• * Batteries will also supply a set amount of voltage (ex. 1.5V, 9V, 12V)
• The unit of voltage is the Volt (V).
5. ### Slide 5 - Electrical Potential Energy

• Voltage is the result of a difference in electrical potential energy.
• This is similar to gravitational potential energy, which makes balls roll down hills.
• In this case charges flow from areas of high potential to low potential.
6. ### Slide 7 - Resistance

• Resistance is an obstacle to the flow of electrons.
• The total resistance of the circuit impacts the amount of current in the circuit.
• The unit of resistance is the Ohm (Ω).
7. ### Slide 8 - Insulators & Conductors

• Different materials and objects have different resistances
• Some objects have a set resistance – like nichrome wire
• Some objects have a variable resistance – like a lightbulb, which has a different resistance when cold v. hot.
• The resistance of an object depends on how tightly the atoms hang on to their electrons.
8. ### Slide 10 - Ohm’s Law

• “The current flow through a conductor is directly proportional to the potential difference and inversely proportional to the resistance.”
• In other words: V = IR  any of these three values can be found as long as the other two are known.
9. ### Slide 11 - Resistance in a Circuit

• When elements are added in series, their total resistance is equal to the sum of their individual resistances:
• Each bulb has a resistance of 0.2 Ω.
• The wire and switch have insignificant resistance.
• What is the total resistance of the circuit?

• 0.3 Ω