Video 6: How Does Ohm's Law Work? (Online Class)

TL;DR

Ohm’s Law relates voltage, current, and resistance through V = IR and can determine the resistor needed to light an LED. In the demonstrated circuit, a 2-volt source and a red LED rated for 20 milliamps require a 100-ohm resistor; the circuit is assembled on a breadboard and powered through a voltage divider connected to a 9-volt battery. Read on for the calculation, setup, and LED polarity details.

Transcript

Mujtaba: Today, we're going to learn about Ohm's Law. Mujtaba: I'm curious how many of you have heard of or know about Ohm's Law? Student: I know. Student: I do. Student: I've yeah, yeah. I've heard about it. Yeah. Mujtaba: So the simplest way it is represented is V equals IR. That is, the voltage drop, or the potential drop across a resistor in th... Read More

Key Insights

• ⚡ Ohm's Law is a fundamental principle in physics that relates voltage, current, and resistance.
• 💦 The voltage drop across a resistor is directly proportional to the current passing through it and inversely proportional to its resistance value.
• 🙂 In a simple circuit with an LED, Ohm's Law can be used to determine the resistor value needed to achieve the desired current for the LED to light up.
• 👫 Different types of LEDs have different current ratings, and the resistor value needs to be adjusted accordingly to match the LED's requirements.
• 👻 Ohm's Law can be applied to various real-life scenarios, allowing for the control and manipulation of current flow in electronic devices and circuits.
• 📽️ Understanding Ohm's Law is a valuable skill for DIY projects and electrical engineering applications.
• ⚡ Other factors, such as voltage dividers, can also be used to control and divide voltage in a circuit based on specific resistor values.

Questions & Answers

Q: What is Ohm’s Law, and how does it work?

Ohm’s Law is represented as V = IR. The voltage drop across a resistor equals the current passing through it multiplied by the resistor’s resistance value.

Q: What do voltage, current, and resistance mean in Ohm’s Law?

Current is the flow of electrons, while voltage is the potential that enables electrons to move from higher potential to lower potential. Resistance opposes that flow, like the friction between boba and a straw in the lesson’s analogy.

Q: How do you calculate the resistor needed for a red LED?

Use V = IR and rearrange it to find the resistance from the known voltage and current. With 2 volts and a red LED requiring 20 milliamps, the calculated resistor value is 100 ohms.

Q: How is the red LED connected in the demonstrated circuit?

The red LED is connected to the 2-volt source through a 100-ohm resistor. Its longer, positive leg goes toward the resistor, while its negative leg connects to ground.

Q: What happens if an LED is connected backward?

LEDs are directional and have two legs. The longer leg is positive, and the LED does not turn on if its legs are connected in the opposite direction.

Q: How does the breadboard connect circuit components?

The breadboard contains groups of holes used to assemble the circuit. In the demonstrated board, five holes in each row are connected to one another, while the columns are not connected.

Q: Why is a voltage divider used in the LED circuit?

The circuit uses a voltage divider to reduce the battery’s voltage to the required input voltage. It takes the 9-volt battery supply and provides 2 volts to the resistor and LED portion of the circuit.

Q: Do red and blue LEDs require the same current?

No, the lesson states that LEDs can have different current ratings depending on their type. The demonstrated red LED requires 20 milliamps, while the blue LED requires 30 milliamps to turn on.

Summary & Key Takeaways

• Ohm's Law, represented by V = IR, states that the voltage drop across a resistor is equal to the current passing through it multiplied by its resistance value.

• A simple circuit with an LED can be used to demonstrate Ohm's Law in action, by finding the appropriate resistor value to achieve the desired current for the LED to turn on.

• Different types of LEDs have different current ratings, and the resistor value needs to be adjusted accordingly to match the LED's requirements.