Tangent Galvanometer - Amrita University

Summary

This video script explains an experiment using a tangent galvanometer to determine the reduction factor and horizontal intensity of Earth's magnetic field. The apparatus includes a tangent galvanometer, commutator, rheostat, and other components. The principle is based on the tangent law, where the deflection of a needle in two perpendicular magnetic fields is used to calculate the horizontal magnetic field intensity. The procedure involves adjusting the galvanometer, applying a current, and measuring the deflection. The experiment can be repeated with different current values and coil turns for accuracy. The tangent galvanometer has applications in measuring small currents and determining Earth's magnetic field.

Takeaways

• 🧲 The tangent galvanometer (TG) is used to determine the reduction factor and the horizontal intensity of Earth's magnetic field.
• 🛠️ The setup includes a TG, commutator, rheostat, regulated DC power supply, ammeter, key, and connecting wires.
• 🌐 The TG consists of a coil wound on a non-magnetic frame which, when energized, produces a magnetic field perpendicular to Earth's magnetic field.
• 📐 The tangent law states that when a magnet is suspended in two magnetic fields, it rests at an angle where the magnetic field due to the current (B) is equal to the horizontal component of Earth's magnetic field (Bh) times the tangent of the angle (B = Bh * tan(theta)).
• 🔋 The magnetic field generated by the current-carrying coil at its center can be calculated using the formula B = (mu_0 * n * I) / (2 * a), where mu_0 is the permeability of free space, n is the number of turns, I is the current, and a is the radius of the coil.
• ⚖️ The reduction factor (K) of the TG is defined as the ratio of the magnetic field produced by the current in the coil to the deflection angle (K = B / tan(theta)).
• 📉 To measure the reduction factor and Earth's magnetic field intensity, the TG is adjusted to align with Earth's magnetic meridian, and the current is varied to achieve a deflection between 30 to 60 degrees.
• 🔄 The experiment involves reversing the current to ensure accurate readings and can be repeated with different current values and coil turns.
• 🔌 Proper connections are made with the power supply, rheostat, commutator, and TG to ensure the correct flow of current and measurement of deflection.
• 🌟 The tangent galvanometer has applications in measuring small currents and determining the horizontal intensity of Earth's magnetic field.

Q & A

What is the primary aim of using a tangent galvanometer?

The primary aim is to determine the reduction factor of the tangent galvanometer and the horizontal intensity of the earth's magnetic field.

What are the main components of the apparatus used in the experiment?

The main components include a tangent galvanometer, commutator, rheostat, regulated DC power supply, ammeter, key, and connecting wires.

How does the tangent galvanometer produce a magnetic field when current is passed through it?

The tangent galvanometer produces a magnetic field at the center of the coil, which is perpendicular to the earth's magnetic field, when current is passed through the circular coil of insulated copper wire.

What is the tangent law in magnetism as mentioned in the script?

The tangent law in magnetism states that when a bar magnet is suspended in two magnetic fields B and Bh, the magnet comes to rest making an angle (theta) with the direction of Bh, and the relationship is given by B = Bh * tan(theta).

How is the reduction factor of the tangent galvanometer defined?

The reduction factor of the tangent galvanometer (K) is defined as the ratio of the horizontal component of the earth's magnetic field (Bh) to the magnetic field generated by the current carrying circular coil (B).

What is the significance of the permeability of free space in the experiment?

The permeability of free space, denoted by μ₀ and equal to 4π × 10^-7 H/m, is used in the formula to calculate the magnetic field generated by the current carrying coil at the center.

What is the procedure for preliminary adjustments before starting the experiment?

The procedure includes adjusting the leveling screws to make the plane of the coil vertical, rotating the compass box so that its 90-90 line is in the plane of the coil, and rotating the tangent galvanometer to align the aluminum pointer with the 0-0 line in the compass box.

How is the current through the galvanometer adjusted for accurate results?

The current is adjusted using the rheostat until the galvanometer shows a deflection between 30 and 60 degrees for better and more accurate results.

What is the purpose of reversing the current using the commutator?

Reversing the current using the commutator allows for noting the corresponding deflection in the compass box, which is necessary for accurate measurements of the earth's magnetic field.

What are the applications of a tangent galvanometer as stated in the script?

A tangent galvanometer can be used for measuring small currents and for the determination of the horizontal intensity of the earth's magnetic field.