Current through resistor in parallel: Worked example | DC Circuits | AP Physics 1 | Khan Academy

TL;DR

Simplify the circuit, calculate the equivalent resistance, and determine the current flow through different resistors using Ohm's law.

Transcript

• [Instructor] So we have an interesting circuit here. The goal of this video is to figure out what is the current that flows through this six-ohm resistor? Pause this video, and see if you can work through it. So the way that I am going to tackle it is first simplify the circuit. Take these two resistors in parallel, and think about what the equiv... Read More

Key Insights

• 👻 Calculating the equivalent resistance allows for simplifying complex circuits.
• 👮 Ohm's law is a useful tool for determining current, voltage, and resistance in a circuit.
• 💦 Voltage drops across resistors can be used to calculate currents flowing through specific resistors.
• ❓ Current can split between different resistors in a circuit, depending on their resistance values.

Questions & Answers

Q: How can the circuit be simplified?

The instructor simplifies the circuit by calculating the equivalent resistance of two resistors in parallel and replacing them with a single resistor. The equivalent resistance is found to be four ohms.

Q: How is the current flowing through the circuit calculated?

The current is calculated using Ohm's law by dividing the voltage drop (24 volts) by the equivalent resistance of the simplified circuit (four ohms). The current is determined to be 4.0 amps.

Q: How is the current flowing through a specific resistor calculated?

To calculate the current flowing through a specific resistor, the voltage drop across it is determined using Ohm's law. The voltage drop is divided by the resistance of the resistor to obtain the current. For the six-ohm resistor, the current is found to be 2.7 amps.

Q: Why does the current split between two resistors?

The current flowing through the first resistor splits between the other two resistors (i2 and i3). This is because the total current entering a point should equal the total current leaving that point. In this case, i2 + i3 should add up to the original current of 4 amps.

Summary & Key Takeaways

• The instructor simplifies the circuit by calculating the equivalent resistance of two resistors in parallel, resulting in a four-ohm resistor.

• The current flowing through the simplified circuit is calculated using Ohm's law, resulting in a current of 4.0 amps.

• By analyzing the voltage drops across resistors, the current flowing through a specific resistor is calculated to be 2.7 amps.