PROJECT ON TANGENT GALVANOMETER, Essays (high school) of Physics

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CERTIFICATE

This is to certify that SNEHA SUMAN BHOI of class XII

completed her PHYSICS project titled " EARTH’S

MAGNETIC FIELD USING A TANGENT

GALVANOMETER " for the academic year 2023- 24

under the supervision of MRS. JYOTIRMAYEE DASH.

he certified student completed her research diligently and

submitted her project on time without missing any

significant project components. It is also certified that this

project is the student's original work and that it can be

submitted for evaluation.

TEACHER PRINCIPAL INTERNAL EXAMINER EXTERNAL EXAMINER

CONTENT

• 1 Introduction SL. NO TITLE PAGE NO
• 2 Tangent Galvanometer 5 -
• 2.1 Working 6 -
• 2.2 Applications
  • 3 Aim of the experiment
  • 4 Apparatus
  • 5 Procedure
  • 6 Observation table
  • 7 Result
  • 8 Conclusion
  • 9 References

1. INTRODUCTION The geomagnetic field, commonly known as the Earth's magnetic field, is the magnetic field that stretches from the Earth's interior to where it meets the solar wind, which is a stream of charged particles emitted by the Sun. The North and South magnetic poles move widely, yet slowly enough that common compasses can still be used for navigation. However, the Earth's field reverses at unpredictable periods of several hundred thousand years, and the north and south magnetic poles abruptly switch locations. These geomagnetic pole reversals leave a record in rocks that paleomagnetic can use to calculate geomagnetic fields in the past. This information is then useful in researching the movements of continents and ocean floors during the plate tectonics process. The magnetosphere is the region above the ionosphere that extends tens of thousands of kilometres into space, shielding the Earth from charged particles in the solar wind and cosmic rays that would otherwise strip away the upper atmosphere, including the ozone layer, which protects the Earth from harmful ultraviolet radiation. The Earth's magnetic field deflects the majority of solar wind, whose charged particles would otherwise deplete the ozone layer, which protects the Earth from damaging UV radiation. One process for stripping is for gas to become trapped in magnetic field bubbles, which are then pulled off by solar winds. The field's strength is commonly measured in gauss (G), but is usually reported in nanoteslas (nT), with 1 G equalling 100,000 nT. A nanotesla is also known as a gamma. The magnetic field, B, is measured in Tesla. The field has a range of around 25,000 to 65,000 nT (0.25-0.65 G). The magnetic field of the Earth can be closely approximated at its surface by the field of a magnetic dipole positioned at the centre of the Earth and tilted at an angle of about 10° with regard to the rotational axis of the Earth. The dipole is analogous to a powerful bar magnet, with its South Pole pointing towards the geomagnetic North Pole. A magnet's north pole is so named because, if allowed to freely rotate, it points nearly northward (in the geographic sense). Because a magnet's north pole attracts the south poles of other magnets while repelling the north poles, it must be attracted to the south pole.

2. TANGENT GALVANOMETER

The tangent galvanometer refers to a device that facilitates the measurement of current. It acts in accordance with the principle of tangent law. Here, a magnetic needle is suspended at a point where the crossing of two fields takes place at right angles to each other. Specifically, this point is where these fields shall come to a state of rest in the direction of the resultant. The tangent galvanometer has a vertical coil of wire. Towards the centre of it is a horizontal magnetic needle. The current, whose measurement is to take place, passes via the coil. Let’s no

The magnetic induction at the centre of the coil due to current in the coil is given by Where k is a constant, called the reduction factor of the tangent galvanometer. ∴ i ∝ tan θ Thus in a tangent galvanometer, the current through the coil is directly proportional to the tangent of the angle of deflection of the needle. Due to this characteristic of the galvanometer is known as the tangent galvanometer. Knowing k and θ we can calculate the value of the current through the coil.

2.2 APPLICATIONS :

T.G can be used to measure the magnitude of the horizontal component of the geomagnetic field. The principle can be used to compare the galvanometer constants.

3. AIM OF THE EXPERIMENT

To study the earth's magnetic field using a tangent galvanometer Tangent galvanometer

4. APPARATUS

Accumulator, Rheostat, Ammeter, Commutator, Tangent Galvanometer

5. PROCEDURE

The circuit is made as shown in the diagram. The plane of the coil is made vertical by adjusting the levelling screws. The plane of the coil is made by adjusting the levelling screws. The plane of the coil is made parallel to (90-90) in the compass box. The whole T.G is rotated to read (0-0) at the ends of the aluminium pointer. Now the plane of the coil is in the magnetic meridian. The Commutator keys are put. The rheostat should be adjusted for deflection in T.G between 10 and 60. For a current I, the deflections of the pointer θ1 & θ2 are noted. The Commutator is reversed. The deflections of the pointer θ3 & θ4 are noted. The average of the four readings is the deflection θ. From the theory of the T.G, I=K tanθ. By varying the current the experiment is repeated. Using a string the circumference of the coil is measured. Hence its radius r is found. Let n be the number of turns of the coil. The horizontal intensity at the place is given by, Bh = μ0nK/2r Fig-2. Circuit Diagram of Tangent Galvanometer

8. CONCLUSION

Experiment in tangent galvanometer gives the reduction factor of galvanometer and horizontal intensity of earth’s magnetic field. 9. REFERENCES 1.https://thefactfactor.com/facts/pure_science/physics/tangent- galvanometer/5924/

2. https://vlab.amrita.edu/index.php?sub=1&brch=192&sim=1049&cnt= 3.https://www.niser.ac.in/sps/sites/default/files/basic_page/Tangent%20Galvan ometer.pdf 4.https://unacademy.com/content/ssc/study-material/general-awareness/tangent- galvanometer/
3. https://testbook.com/physics/tangent-galvanometer