Animation of how the Galvanometer works (English subtitle)

Summary

In this tutorial, we explore how a galvanometer works by combining concepts like Lorentz force, torque, and Newton's laws. When an electric current flows through a coil inside a galvanometer, it interacts with a magnetic field, causing the coil to rotate. The rotation is stopped when the torque from the spiral spring balances the force from the current. The video explains the behavior of the galvanometer in simple terms and provides insights into how these physical principles are applied to make galvanometers work. The next tutorial will analyze these concepts in more mathematical detail.

Takeaways

• 😀 The galvanometer needle deflects based on the direction of electric current entering the positive terminal.
• 😀 The main components of a galvanometer are magnets, coil windings, needles, spiral springs, and scales, though this can be simplified to a magnet and a coil for animation purposes.
• 😀 A magnetic field is generated around a magnet, with field lines running from the north pole to the south pole.
• 😀 An electric current flows from the positive to the negative terminal, represented by arrows showing the direction of the current.
• 😀 The Lorentz force acts on a wire running through an external magnetic field, affecting the direction of the force based on the position of the wire.
• 😀 The right-hand rule helps determine the direction of the Lorentz force on the wires: downward for the right wire and upward for the left wire.
• 😀 Both wires experience the same magnitude of the Lorentz force but in opposite directions, resulting in a net force of zero in the vertical direction (ΣFᵧ = 0).
• 😀 Despite no net vertical force, the coil experiences torque due to the forces having different torque arms, leading to rotational motion.
• 😀 The coil will rotate clockwise due to the net torque acting on it, even though the forces are balanced in the vertical direction.
• 😀 The spiral springs in the galvanometer balance the torque, causing the needle to stop at a specific angular position once the forces are balanced.
• 😀 Without spiral springs, the coil would continue to rotate as long as the current flows, similar to the behavior of a fan.
• 😀 The concepts of Lorentz force, torque, and Newton's laws work together to make the galvanometer function effectively.

Q & A

What happens when a positive current enters the positive terminal of a galvanometer?

The galvanometer needle deviates to the right when a positive current enters the positive terminal.

How does the galvanometer needle react when the current direction is reversed?

When the current direction is reversed, the galvanometer needle turns to the left.

What are the main components inside a galvanometer?

The main components inside a galvanometer include permanent magnets, wire or coil windings, needles, spiral springs, and scales.

What simplifications are made in the animation of a galvanometer?

In the animation, the complex components of a galvanometer are simplified into just a magnet and a coil.

What is the role of the magnetic field in a galvanometer?

The magnetic field in a galvanometer is created by the permanent magnet, with magnetic field lines running from the north pole to the south pole.

What does the current flow through in a galvanometer?

In a galvanometer, the electric current flows from the positive terminal through the coil to the negative terminal.

How does the Lorentz force affect the coil in a galvanometer?

The Lorentz force affects the coil by exerting a downward force on the wire on the right and an upward force on the wire on the left, leading to a torque that causes the coil to rotate.

What concept is used to explain the rotation of the coil in a galvanometer?

The concept of torque is used to explain the rotation of the coil in a galvanometer, as the forces on both sides of the coil create a torque that causes it to rotate.

Why does the galvanometer needle stop at a certain point?

The galvanometer needle stops at a certain point because the torque from the spiral spring balances out the torque from the coil's rotation, preventing further movement.

What would happen to the coil in a galvanometer without the spiral spring?

Without the spiral spring, the coil in the galvanometer would continue rotating as long as the electric current is flowing, similar to a fan.

How are the concepts of Lorentz force, torque, and Newton's laws applied in a galvanometer?

In a galvanometer, the Lorentz force causes the coil to experience torque, which leads to rotation. The spiral spring reacts to this torque, and Newton's laws govern the interaction between the forces and the resulting motion.