Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current...
Transcript of Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current...
![Page 1: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/1.jpg)
Ohm’s Law &
Resistors
![Page 2: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/2.jpg)
Single Bulb Circuit
How does voltage affect current flow?
Qualitatively: Increasing voltage
(adding more batteries) causes a larger current flow
Quantitatively:
?
![Page 3: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/3.jpg)
Single Bulb Circuit
How does voltage affect current flow?
Voltage (V) Current (A)
0.0 0.0
1.5 0.100
3.0 0.200
4.5 0.300
6.0 0.400
![Page 4: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/4.jpg)
Single Bulb Circuit
How does voltage affect current flow?
Linear Relationship – Known as Ohm’s Law
![Page 5: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/5.jpg)
Ohm’s Law (Conceptually) • The current through a conducting material
is directly proportional to the voltage across the material
5V 200mA
10V 400mA
Current through Bulb 1
150mA
300mA
Current through Bulb 2
Current flows less easily through Bulb 1 than Bulb 2 Bulb 2 has more resistance than Bulb 1
![Page 6: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/6.jpg)
Single Bulb Circuit
How does voltage affect current flow?
I = 0.6667A1.0V
⎛
⎝⎜
⎞
⎠⎟⋅ΔV
![Page 7: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/7.jpg)
Single Bulb Circuit
How does voltage affect current flow?
I = 0.667A1.0V
⎛
⎝⎜
⎞
⎠⎟⋅ΔV
Light Bulb’s Electrical Conductance
For every additional 1.0V increase in voltage of the batteries, there will be
0.667A more current flowing through the bulb
![Page 8: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/8.jpg)
Electrical Conductance
I =G ⋅ ΔVG stands for Electrical Conductance • how easily current flows through a circuit element
(like a bulb) • Larger Conductance = Easier for Charges to Flow • SI Units: A / V
The inverse of Electrical Conductance is called Electrical Resistance (R) • the difficulty with which current flows through a
circuit element • Larger Resistance = Harder for Charges to Flow
![Page 9: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/9.jpg)
Electrical Conductance vs. Resistance
I =G ⋅ ΔV I = 1R⋅ ΔV
ΔVI= R
ΔV = I ⋅R
This is the mathematical
representation of Ohm’s Law
![Page 10: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/10.jpg)
Ohm’s Law
• The current through a conducting material is directly proportional to the voltage across the material
ΔVI= R
• R stands for Electrical Resistance • SI Unit: Ohm (Ω) 1Ω = 1 V/A
![Page 11: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/11.jpg)
Conceptual Example
• A certain conductor has a resistance of 150Ω. What does this mean?
A potential difference (voltage) of 150V is required to cause 1A of current to flow.
A potential difference (voltage) of 300V is required to cause 2A of current to flow.
![Page 12: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/12.jpg)
Quantitative Example
• A conductor is known to have a resistance of 400Ω. It’s plugged into a wall (120V outlet). What will be the current flowing through the conductor?
ΔV = I ⋅R120V = I ⋅ (400Ω)I = 0.30A = 300mA
ΔV=120V R = 400Ω
I = ?
KLuES:
![Page 13: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/13.jpg)
Your Turn
• ER WS 1, #1
![Page 14: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/14.jpg)
Ohm’s Law Limitations
• Ohm’s Law can only be applied to ohmic materials (materials in which we see the linear pattern between ΔV and I)
• Some ohmic materials may become non-ohmic at very hot or low temperatures
![Page 15: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/15.jpg)
Resistors
• Circuit elements that reduce/impede current flow
• Purpose: To protect devices that can be damaged by large currents
• Generally Ohmic under normal conditions
![Page 16: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/16.jpg)
![Page 17: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/17.jpg)
R R Br O B V Br Bl R
22 x 101 Ω 220 Ω
36 x 107 Ω 360,000,000 Ω
10 x 102 Ω 1000 Ω
![Page 18: Ohm’s Law Resistors - SOF Physics! - Home PPT 1 Ohm...Ohm’s Law (Conceptually) • The current through a conducting material is directly proportional to the voltage across the](https://reader033.fdocuments.in/reader033/viewer/2022051800/5acbcd517f8b9aa1518b8956/html5/thumbnails/18.jpg)
Your Turn
• ER WS 1, #2