Galvanometer | moving coil galvanometer 12th class explanation construction and working animation HD

Summary

This video delves into the workings of a Permanent Magnet Moving Coil Galvanometer, an electromechanical device for detecting and indicating electric currents as low as a few microamperes. It features a rectangular coil within a magnetic field, which experiences torque resulting in pointer deflection. The video explains the construction, including the concave magnets for a radial magnetic field, ensuring a constant torque for accurate measurements. It also covers the principle of operation based on the interaction of current and magnetic field, highlighting the importance of calibration for precise current measurement.

Takeaways

• 📚 A galvanometer is an electromechanical instrument used to detect and indicate electric current.
• ⚡ It is highly sensitive and can measure low currents, even in the microampere range.
• 🔄 A galvanometer operates by producing a rotary deflection in response to an electric current in a magnetic field.
• 🧲 The Permanent Magnet Moving Coil Galvanometer uses two concave permanent magnets and a rectangular coil.
• 🌀 The coil, made of thinly insulated copper wire, is wound on a metallic frame and can rotate about a fixed axis.
• 🪡 The device features two phosphor bronze hair-like springs to ensure proper functioning and prevent unnecessary deflection.
• 💡 A soft iron core inside the coil improves the magnetic field's strength and makes it radial.
• 🧮 The principle of operation is that a current-carrying coil in a magnetic field experiences torque, causing angular deflection.
• ↔️ The radial magnetic field ensures constant torque and makes the deflection directly proportional to the current.
• 📏 The galvanometer has a calibrated scale to convert the angular deflection of the pointer into microamperes for measurement.

Q & A

What is a galvanometer and what is its primary use?

A galvanometer is an electromechanical instrument used for detecting and indicating electric current. It is a sensitive electromagnetic device capable of measuring low currents, even down to a few microamperes.

How does a Permanent Magnet Moving Coil Galvanometer produce a response to electric current?

A Permanent Magnet Moving Coil Galvanometer works as an actuator by producing a rotary deflection in response to an electric current flowing through a coil in a constant magnetic field.

What are the main components of a Permanent Magnet Moving Coil Galvanometer?

The main components include two concave permanent magnets, a rectangular coil wound with many turns of fine copper wire, a metallic frame, two phosphor bronze springs, and a soft iron core positioned inside the coil.

What is the role of the soft iron core in the galvanometer?

The soft iron core is symmetrically positioned inside the coil to improve the strength of the magnetic field and to make the field radial, which is important for the proper functioning of the galvanometer.

Why is it important for the magnetic field to be radial in a galvanometer?

A radial magnetic field is important because it ensures that the magnetic field and the area vector of the coil are always at a right angle, providing a constant torque irrespective of the coil's rotation.

How does the hair spring contribute to the functioning of the galvanometer?

The hair spring provides a counter torque that resists any extra or unnecessary deflection, protecting the sensitive pointer and ensuring the proper functioning of the galvanometer.

What principle does the Permanent Magnet Moving Coil Galvanometer operate on?

It operates on the principle that a current-carrying coil placed in a magnetic field experiences a torque, causing angular deflection of the pointer.

What is the significance of the equation N I A B Sin theta in the context of a galvanometer?

The equation represents the torque experienced by the coil, where N is the number of turns, I is the current, A is the area of the coil, B is the magnetic field strength, and theta is the angle between the magnetic field and the area vector.

Why is the angular deflection of the pointer directly proportional to the current in a galvanometer?

The angular deflection is directly proportional to the current because, with a radial magnetic field, N, A, and B are constant, and theta becomes constant at ninety degrees, making I the only variable.

How is the angular deflection of the pointer related to the current being measured?

The angular deflection of the pointer is used to measure the current indirectly through a calibrated scale that converts the deflection into a measure of current in microamperes.

What is the purpose of the calibrated scale in a galvanometer?

The calibrated scale is provided to convert the angular deflection of the pointer into a measure of the electric current, allowing for accurate current measurements.