Induksi Elektromagnetik • Part 3: Hukum Lenz Pada Loop Kawat

Summary

This video tutorial provides a comprehensive explanation of electromagnetic induction, focusing on Lenz's Law. It covers the concept that the induced electromotive force (EMF) generates a current whose magnetic field opposes the change in flux. The script introduces key formulas and explains how to apply them, including the calculation of induced EMF and current in various examples. It also demonstrates the right-hand rule for determining the direction of the induced current. This educational content is designed to help viewers understand these fundamental principles of physics, with practical examples to aid learning.

Takeaways

• 😀 The video focuses on electromagnetic induction and Lenz's Law, specifically in the context of a loop of wire.
• 😀 Lenz's Law states that the induced electromotive force (EMF) always generates a current whose magnetic field opposes the change in flux.
• 😀 The formula for calculating induced EMF is: ε = -NBLv, where N is the number of wire turns, B is the magnetic field strength in Tesla, L is the wire length in meters, and v is the velocity in meters per second.
• 😀 Induced current (I_in) can be calculated using Ohm's Law: I_in = ε / R, where R is the resistance in ohms.
• 😀 The direction of the induced current can be determined using the right-hand rule, similar to the Lorentz force law.
• 😀 For the right-hand rule, point your fingers in the direction of the magnetic field (B), your thumb in the direction of the wire's motion (v), and your palm will show the direction of the induced current.
• 😀 In the example with wire PQ, when moved with velocity 4 m/s in a magnetic field of 0.2 Tesla, the induced EMF was calculated to be 0.2 V.
• 😀 The direction of the induced current in wire PQ is upwards, as determined by the right-hand rule.
• 😀 In another example, a wire AB moved at 5 m/s in a magnetic field of 2.5 × 10⁻⁴ Tesla, resulting in an induced EMF of 3.75 × 10⁻⁴ V and a current of 2.5 × 10⁻⁵ A.
• 😀 The current in wire AB flows upwards, from point B to point A, as determined by the right-hand rule, confirming the role of Lenz's Law in opposing the change in flux.

Q & A

What does Lenz's Law state about induced electromotive force (EMF)?

Lenz's Law states that the induced electromotive force (EMF) always generates a current whose magnetic field opposes the change in the original magnetic flux.

How is the induced EMF formula derived and what does it represent?

The formula for induced EMF is ε = N * B * L * V, where N is the number of coil turns, B is the magnetic field strength in Tesla, L is the length of the wire in meters, and V is the velocity of the wire in meters per second.

What is the relationship between induced EMF and the induced current in the circuit?

The induced current (I_in) is determined by dividing the induced EMF (ε) by the resistance (R) of the circuit, as given by the formula I_in = ε / R, where ε is the induced EMF in volts, and R is the resistance in ohms.

How do we determine the direction of the induced current according to Lenz's Law?

To determine the direction of the induced current, we use the right-hand rule. Point the fingers in the direction of the magnetic field (B), and the thumb in the direction of the velocity (V) of the wire. The palm then shows the direction of the induced current.

What does the term 'cross' in magnetic field direction indicate?

The term 'cross' in magnetic field direction means that the magnetic field is directed into the plane of the paper or screen, away from the observer.

What does 'dot' in magnetic field direction represent?

The term 'dot' in magnetic field direction indicates that the magnetic field is directed out of the plane of the paper or screen, towards the observer.

In the example with wire PQ, how is the induced EMF calculated?

In the example with wire PQ, the induced EMF is calculated using the formula ε = N * B * L * V. With one coil turn (N=1), a magnetic field strength of 0.2 Tesla (B), wire length of 0.25 meters (L), and velocity of 4 m/s (V), the induced EMF is found to be 0.2 volts.

What is the significance of the direction of the induced current in the example with wire PQ?

The direction of the induced current in the example with wire PQ is determined using the right-hand rule. With the velocity to the right and the magnetic field entering the page, the current flows upward along the wire, from Q to P.

How is the induced EMF and current calculated in the example with wire AB?

In the example with wire AB, the induced EMF is calculated using the formula ε = N * B * L * V. With a magnetic field of 2.5 x 10^-4 Tesla, wire length of 0.3 meters, and velocity of 5 m/s, the induced EMF is 3.75 x 10^-4 volts. The current is then calculated as I_in = ε / R, which results in a current of 2.5 x 10^-5 A.

What does the negative sign in the calculation of induced EMF represent?

The negative sign in the induced EMF calculation indicates the direction of the induced EMF and current, in accordance with Lenz's Law, which states that the induced current opposes the change in magnetic flux.