2.3 - Ohm’s Law
Enroll to start learning
You’ve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Understanding Ohm's Law
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Today, we are diving into Ohm's Law, which explains the relationship between voltage, current, and resistance. Can anyone tell me the formulas associated with this law?
Isn’t it V = I times R?
Exactly! V = I * R tells us how voltage (V) is equal to the current (I) flowing through a conductor multiplied by the resistance (R) of that conductor. Why do we think this relationship is important?
Because it helps us calculate how much current flows based on voltage and resistance?
Right! Understanding this relationship allows us to make predictions in electrical circuits. Remember, Ohm's Law applies well to ohmic conductors, where the relationship is linear. Can anyone describe what that means?
I think it means that if you plot voltage versus current, you get a straight line!
That's correct! The straight line indicates a constant resistance. Great job!
Breaking Down the Equation
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Let’s break down the components of our formula V = I * R. What do we mean by each of those variables?
V is voltage, I is current, and R is resistance.
Correct! Now, if we rearranged this formula to find the current, what would it look like?
It would be I = V divided by R, right?
Exactly! So if we know the voltage and resistance of a circuit, we can easily calculate the current flowing through it. How about we do a practical example?
Sure! What values should we use?
Let’s say we have a voltage of 10 volts and a resistance of 5 ohms. What is the current?
Using I = V / R, it would be 10 volts divided by 5 ohms, which is 2 amperes!
Great job, class! That’s exactly how you apply Ohm’s Law!
Graphing Ohm's Law
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Now that we understand the formula, let's talk about how this relationship looks graphically. What might a graph of voltage versus current look like for an ohmic conductor?
It should be a straight line through the origin.
Yes! A straight line indicates a constant resistance. The slope of this line represents the resistance, R. What's important to remember about this graphic representation?
It shows that as you increase voltage, current increases linearly?
Exactly! If the resistance remains the same, the current will rise directly with an increase in voltage. This concept is essential when analyzing circuits. Any questions?
What happens if the resistance increases?
Good question! An increase in resistance at constant voltage results in a decrease in current. That’s the beauty of Ohm’s Law!
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
Ohm's Law, formulated by Georg Simon Ohm, establishes that the current flowing through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance of the conductor. This relationship is key to understanding how electric circuits function.
Detailed
Ohm’s Law
Ohm’s Law, proposed by Georg Simon Ohm, is fundamental in the study of current electricity. It defines the relationship between voltage (V), current (I), and resistance (R) in a circuit. Mathematically, it is expressed as:
\[ V = I \cdot R \]
Where:
- V is the potential difference (voltage) applied across the conductor,
- I is the current flowing through the conductor,
- R is the resistance of the conductor.
The implication of Ohm's Law is that for passive components (ohmic conductors), a graph of voltage (V) versus current (I) yields a straight line, confirming that voltage and current are linearly related under constant resistance conditions. This principle is foundational for analyzing electrical circuits, allowing for predictive calculations of current flows given certain voltages and resistances.
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Understanding Ohm’s Law
Chapter 1 of 2
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
• Proposed by Georg Simon Ohm.
𝑉 = 𝐼𝑅
where
𝑉 = potential difference,
𝐼 = current,
𝑅 = resistance.
Detailed Explanation
Ohm's Law is a fundamental principle in electrical engineering that relates voltage (V), current (I), and resistance (R) in a circuit. According to Ohm's Law, the potential difference (voltage) across a conductor is directly proportional to the current flowing through it, with the resistance of the conductor acting as the proportionality constant. This means if you know any two of these quantities, you can calculate the third. This relationship is expressed mathematically as V = I × R.
Examples & Analogies
Think of a garden hose. The water pressure in the hose represents voltage (V), the flow of water is similar to current (I), and the size of the hose is like resistance (R). If you increase the water pressure, more water flows through the hose (if the size is the same), similar to how increasing voltage increases current in a circuit.
Graphical Representation
Chapter 2 of 2
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
• Graph of 𝑉 vs 𝐼 is a straight line for ohmic conductors.
Detailed Explanation
In a graph where voltage (V) is plotted on the y-axis and current (I) is plotted on the x-axis, ohmic conductors will show a linear relationship between these two quantities. This means that as the current increases, the voltage also increases proportionally, creating a straight line on the graph. The slope of this line represents the resistance (R) of the conductor. A steeper slope indicates higher resistance, while a flatter slope indicates lower resistance.
Examples & Analogies
Imagine a slope on a hill. The steeper the hill, the harder it is to climb up; the same idea applies to electrical resistance. A steep slope on the V-I graph means a higher resistance, just as climbing a steep hill requires more effort than a gentle incline.
Key Concepts
-
Ohm's Law: Defines the linear relationship between voltage, current, and resistance in a circuit.
-
Voltage: The potential difference that drives current through a conductor.
-
Current: The flow of electric charge in a circuit.
-
Resistance: The opposition to the flow of current in a circuit.
Examples & Applications
If a circuit has a voltage of 12V and a resistance of 4Ω, then according to Ohm's Law, the current can be calculated as I = V/R = 12V/4Ω = 3A.
A light bulb rated at 60W connected to a 120V outlet would have an equivalent current of 0.5A, calculated using P = IV (where P is power).
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
Ohm's Law is quite neat, voltage and current meet. Resistance is the key, just remember, V, I, R—it's easy!
Stories
Once in a village, a wise man named Ohm taught everyone that the more voltage you give to the wire, the more current will flow, but only if the resistance allows it. They called it Ohm’s Law as they learned to build their electric lanterns.
Memory Tools
Remember 'VIR' for Voltage = Current times Resistance.
Acronyms
VIR
for Voltage
for Current
for Resistance.
Flash Cards
Glossary
- Voltage (V)
The electric potential difference between two points in a circuit, measured in volts (V).
- Current (I)
The rate of flow of electric charge through a conductor, measured in amperes (A).
- Resistance (R)
A measure of the opposition to current flow in a conductor, measured in ohms (Ω).
- Ohmic Conductors
Materials that obey Ohm's Law (V= IR), where the relationship between voltage and current is linear.
Reference links
Supplementary resources to enhance your learning experience.