What is Electromagnetic Induction? | Faraday's Laws and Lenz Law | iKen | iKen Edu | iKen App

Summary

This lesson explores electromagnetic induction, demonstrating how a moving magnet near a solenoid induces current, as shown by a galvanometer's deflection. Faraday's laws highlight that an electromotive force (EMF) is induced when there's a change in magnetic flux linked with a coil, with the induced EMF's direction determined by the right-hand rule. Lenz's law explains that the induced EMF opposes the change in magnetic flux, adhering to the conservation of energy and Newton's third law.

Takeaways

• 🌐 Electromagnetic induction occurs when there is relative motion between a magnet and a coil, causing a change in magnetic flux through the coil.
• 📡 The initial reading of the galvanometer is zero, indicating no current flow when the magnet is stationary.
• 👉 The direction of galvanometer deflection changes based on the direction of the magnet's movement relative to the solenoid.
• 🔄 The polarity of the induced current in the solenoid is affected by the magnet's polarity and its direction of approach or withdrawal.
• ⚡ The strength of the induced current can be increased by using a stronger magnet, increasing the magnet's velocity, or by increasing the coil's area or the number of turns.
• 🔧 Faraday's laws of electromagnetic induction state that an electromotive force (EMF) is induced in a coil when there is a change in magnetic flux linked with it, and the magnitude of this EMF is proportional to the rate of change of the magnetic flux.
• 🤚 Fleming's right-hand rule helps determine the direction of the induced current in a conductor moving through a magnetic field.
• 🛡 Lenz's law states that the direction of the induced EMF is such that it opposes the change in magnetic flux that produces it, adhering to the conservation of energy.
• 🔄 Newton's third law of motion is reflected in Lenz's law, as every action has an equal and opposite reaction, indicating that induced currents create magnetic fields that oppose the change causing the induction.
• 🔄 The experiment demonstrates that no current flows when there is no relative motion between the magnet and the coil, as the magnetic flux remains constant.
• 🔌 A complete circuit is necessary for the induced EMF to cause a current to flow through the coil, illustrating the relationship between EMF, magnetic flux, and current.

Q & A

What is electromagnetic induction?

Electromagnetic induction is the process by which a change in magnetic flux through a coil induces an electromotive force (EMF), resulting in the flow of current if the circuit is complete.

How is the experiment demonstrating electromagnetic induction set up?

The experiment involves binding an insulated copper wire to form a solenoid, connecting the ends to a galvanometer, and observing the galvanometer's response when a magnet is moved towards or away from the solenoid.

What happens when the magnet is stationary near the solenoid?

When the magnet is stationary, there is no change in magnetic flux, and the galvanometer reads zero, indicating no current flow in the solenoid.

In which direction does the galvanometer deflect when the North Pole of the magnet is moved towards the solenoid?

The galvanometer deflects towards the right when the North Pole of the magnet is moved towards the solenoid.

What occurs when the magnet is moved away from the solenoid?

When the magnet is moved away from the solenoid, current flows in the opposite direction, causing the galvanometer to deflect towards the left.

How does the velocity of the magnet affect the deflection of the galvanometer?

The faster the magnet is moved away from the solenoid, the greater the deflection of the galvanometer, indicating a stronger induced current.

What does Faraday's observation about current flow in the coil tell us?

Faraday observed that current flows in the coil only when there is relative motion between the coil and the magnet, indicating that a change in magnetic flux is necessary for electromagnetic induction.

What are Faraday's laws of electromagnetic induction?

Faraday's laws state that an electromotive force is induced whenever there is a change in magnetic flux linked with a coil, and the magnitude of the induced EMF is directly proportional to the rate of change of the magnetic flux.

What is Fleming's right-hand rule, and how is it used in generators?

Fleming's right-hand rule is used to determine the direction of the induced current in a generator. It involves stretching the thumb, forefinger, and middle finger of the right hand perpendicular to each other, with the thumb representing the conductor's movement, the forefinger the magnetic field, and the middle finger the induced current direction.

What does Lenz's law state, and how does it relate to Newton's third law of motion?

Lenz's law states that the polarity of the induced EMF is such that it produces a current whose magnetic field opposes the change causing it. It obeys Newton's third law of motion, which states that every action has an equal and opposite reaction, and is based on the conservation of energy.

How can the current in the coil be increased according to Faraday's laws?

The current in the coil can be increased by using a stronger magnet, increasing the motion of the magnet, increasing the area of the coil, or increasing the number of turns in the coil, all of which affect the rate of change of magnetic flux.