SCHOOL NAME SCHOOL NAME SCHOOL NAME - ammhu.com Galvanometer111.pdfIt works on the principle of...

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www.ammhu.com A categorized blogging website and an Online Resource Centre For CBSE, RBSE, and Other State Boards — Raj Kumar Parashari, Head Science @ JPHS, Jaipur-302021

SCHOOL NAME SCHOOL NAME SCHOOL NAME

ADDRESS WITH PINCODE AND PHONE NUMBER

Submitted by Guided by

Student Name [ ]

Class With Section Teacher Name

Class Roll No. Designation

Board Roll No.

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INDEX

1. CERTIFICATE

2. ACKNOWLEDGEMENT

3. AIM

4. APPARATUS REQUIRED

5. PRINCIPLE / THEORY

6. CIRCUIT DIAGRAMS & IMAGES

7. PROCEDURE

8. OBSERVATIONS

9. CALCULATIONS

10. RESULT

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CERTIFICATE

This is to certify that _______________________

student of ______ school name _______, class XII Sc __

has carried out his work for the investigatory project

entitled _______________________________________

under my guidance and supervision.

Signature of the Teacher

Designation

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ACKNOWLEDGEMENT I __________________________________ a student of

____________________________________,______________

would like to pay my sincere gratitude to my Physics teacher

Mr. __________________________ for helping and guiding

me throughout the completion of the project report. I would

like to thank Mr./Mrs. _______________________ our school

principal/Director for making school such a wonderful place of

learning. I also would like to thank Mr. ________________

our lab assistant for the timely assistant in completion of the

project.

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AIM

1. To Determine Reduction Factor (K) Of The given Tangent

Galvanometer.

2. To Find Out Horizontal Component Of Earth’s Magnetic Field

(BH).

APPARATUS REQUIRED

1. Tangent Galvanometer (TG)

2. Commutator (C)

3. Rheostat (Rh)

4. Battery (E)

5. Ammeter (A)

6. Key (K)

7. Sprit Level

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THEORY

It works on the principle of tangent law, according to which,

when a bar magnet is suspended freely inside two mutually

perpendicular magnetic fields B and BH, it comes to rest making

an angle with the direction of BH; such that

B = BH tan

WORKING

Tangent galvanometer is an instrument for calculating small

electric currents by measuring deflection in the in the magnetic

compass placed inside two mutually perpendicular magnetic

fields B and BH.

Tangent Galvanometer consists of a coil of insulated copper

wire wound on a circular non-magnetic frame. When a current is

passed through the circular coil, a magnetic field (B) is produced

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at the centre of the coil in a direction Perpendicular to the plane

of the coil. The TG is arranged in such a way that the horizontal

component of earth’s magnetic field (BH) is in the direction of

the plane of the coil i.e. its plane is in the magnetic meridian. As

magnetic needle is under the action of two mutually

perpendicular fields, it will experience torques due to both

magnetic fields in opposite sense. If is the deflection of the

needle with BH, then according to tangent law,

B = BH tan……….. (1)

Let I is the current passing through the coil of radius ‘a’ with n

turns, then the strength of magnetic field generated by the

current carrying circular coil is,

0nI

B ..............( 2 )2a

Equation (1) and (2), we get

0 32

H

n I. B tan ............( )

a

0

24Ha B

I tan ............( )n

5I K tan ............( )

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Thus current ‘I’ through the coil is directly proportional to

tan . Here, the proportionality constant0

2 Ha BK

n

, is called as the

reduction factor of the given tangent galvanometer. It can be

calculated by finding slope of I v/s tan graph

As reduction factor is 0

2 Ha BK

n

is known, so we can find BH by

substituting radius of the coil a, number of turns n and the

reduction factor K in the following relation.

0 62

H

nKB ..................( )

a

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Tangent Galvanometer Setting and Circuit Diagram :

Connections are made as shown in the figure given below,

where K is the key, E the battery, A the ammeter, Rh the

rheostat, C the commutator, and TG the tangent galvanometer.

The commutator can reverse the current through the TG coil

without changing the current in the rest of the circuit. Taking the

average of the resulting two readings for deflection averages out

any small error in positioning the TG coil relative to the earth’s

magnetic field Bh.

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PROCEDURE

The plane of the coil is made vertical by adjusting the

leveling screws and attached sprit level.

The compass box alone is rotated so that the 90-90 line

in the compass box is in the plane of the coil.

The T.G as a whole is rotated till the Aluminum pointer

reads 0-0.

Note down the number of turns in the coil

A suitable current is allowed to pass through the coil.

Note down the current as well as the deflection in T.G.

Reverse the current and note the deflection values of

current.

Repeat the produce for different values of current.

Measure the radius of the coil from its perimeter.

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OBSERVATIONS AND CALCULATIONS

Number of turns in the coil n = 2 & 50

Internal Diameter D1 = ……… cm

Outer Diameter D2 = …………

Mean diameter, D = 1 2

2

D D cm

So mean radius of the coil a = D/2

Case (A) Number of turns n = 2

S.No.

Ammeter

reading

I(A)

Pointer

deflection in

degrees

Mean

tan

K=I/tan

(A)

direct reverse

2 3 4

1.

2.

3.

4.

5.

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Case (A) Number of turns n = 50

S.No.

Ammeter

reading

I(A)

Pointer deflection

in degrees

Mean

tan

K=I/tan (A)

direct reverse

4

1.

2.

3.

4.

5.

Graph 1 Take reading and draw graph (straight line passing

through origin).

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Graph 2

Take reading and draw graph (straight line passing through

origin).

Form Graph:

(a) Calculation Of Reduction Factor

The slope of the graph from table 1

1

AB ..............K Slope

OB ..............

the slope of the graph from table 2

2

AB ..............K Slope

OB ..............

Thus the reduction factor of the tangent galvanometer

1 2

2

K KK

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(b) Calculation Of Horizontal Component Of Earth

Magnetic Field

From The slope of graph 1

0 14 2

2 2H

nK KB

a ....

From The slope of graph 2

0 24 2

2 2H

nK KB

a ....

Average value of earth’s horizontal component on the place

of experiment is BH = ……….. Tesla

Precautions

a) Keep the tangent galvanometer at large distance from rest of

the apparatus.

b) Plane of the tangent galvanometer must be in the plane of

magnetic meridian.

c) The current should be adjusted so that the deflection in the

tangent galvanometer lies between 30° to 60° .

d) Read both ends of the pointer also make the use of reversing

current direction.

e) While reading the ends of the pointer, error due to pointer

should be avoided.

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Bibliography

1.

2.

Note: — Hand written Investigatory Project Report

should be submitted. Work should be neat and clean.

Avoid unnecessary fancy decoration of the project

report.

Note: — Take readings, draw graph current v/s tan for

each liquid. Find the slope,which will give you the

reduction factor. Follow up suggestions as given.

Note: — Learn theory, working and related viva for

board practical examination.

Wish you all the best.

Raj Kumar Parashari

Head Science

JPHS, Jaipur

Date post:	08-Sep-2019
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