Physics Times 07.2019

tan

H

B

B

 tan^0

H 2

ni

B

r



 


0

(^2) tan tan

 
  
 
i r BH K
n
 i Ktan
Where K is called as T.G. constant (or) reduction
factor of T.G., r-radius of the coil in meter;
BH Horizontal component of earth’s magnetic
field in tesla;
icurrent in amperes

15. Deflection Magnetometer
    (I)Tan A position : In this position the
    magnetometer is set perpendicular to magnetic
    meridian so that, magnetic field due to magnet,
    is in axial position and perpendicular to earth’s
    field.
    18. Magnetic Susceptibility

0

2 2 2

2

tan.

H 4 ( )

M r

B

r l







 



0

3

tan.^2

H 4

B M

r

 

 (r>>l)

(II)Tan B position : The arms of magnetometer

are set in magnetic meridian, so that the

magnetic field due to magnet is at its equatorial

position,

20. Relative permeability

0

Htan 4 .( 2 2 3/2)

B M

r l

 









0

Htan 4. 3

B M

r

 







(r>>l)

(III) Comparison of magnetic moments :

According to deflection method

1 1

2 2

tan

tan

M

M







According to null deflection method

3

1 1

2 2

M d

M d

 

 

 

16. 
    

    Magnetic Field Intensity (^) (H)
    
     The force experienced by unit north pole of one
    weber is called magnetic field strength or intensity
    of magnetic field strength. i.e., H = F / m
     SI unit : Am^1 or weber

    
    


17. 
    

    Intensity of Magnetisation(I)

    
    

 

 

2

2

M m l m

I

V A l A

  

Where m = pole strength; M= Magnetic moment

a = area of cross-section of the magnet;

V=Volume of the magnet

SI unit : Am^1

 

I

H



It has no units

19. Magnetic permeability  

i.e.,

B

H



 It is a scalar having unit Hm^1

 r

0

r

 



 It has no units and dimensions

21. Relation between r and 

As



15. Deflection Magnetometer
    16. Magnetic Field Intensity
    



17. Intensity of Magnetisation(I)


18. Magnetic Susceptibility


19. Magnetic permeability



20. Relative permeability



21. Relation between and


22. Curie’s Law:

0

r

 

^   r  ^1 

22. Curie’s Law:
    It states that intensity of magnetisation (I) and
    hence  are inversely proportional to the absolute
    temperature (T)

i.e.,

C

T

 where C- Curie constant