how does a dip circle measures the dip angle at a place?
 
also explain this statement:
 
the dip angle in a vertical plane perpendicular to magnetic meridian will 90 degrees. 
 
whyy?

Asked by devanshmalhotra2609 | 21st Jan, 2016, 06:54: PM

Expert Answer:

Dip circle use to measure the dip angle.

To use the dip circle: (follow the given image)

(i)     Adjust the leveling screw till the base is horizontal and V inside the box is vertical

(ii)    Rotate the box B till the ends of magnetic needle NS read 90° - 90° on the vertical scale.

The needle is thins position is aligned with the vertical component of earth’s filed. The horizontal component of earth’s field being perpendicular to this plane does not affect the needle.

The reading of the vernier V’ is noted on horizontal circular scale C.

(iii)   Rotate the box exactly through 90° from this position. The plane of vertical scale V is now in magnetic meridian. The total field strength R of earth’s magnetic field is in the same plane and hence magnetic needle rests along begin mathsize 12px style rightwards arrow for straight R of end style. Angle which begin mathsize 12px style rightwards arrow for straight R of end style makes the horizontal direction in magnetic meridian is the angle of dip. As horizontal line is marked 0 – 0, the reading of the ends magnetic needle on the vertical scale give us directly the angle of dip (δ)

At different places on the surface of earth, δ is different.  

begin mathsize 12px style In space vertical space palne space at space an space angle space straight delta space to space the space magnetic space meridian straight H apostrophe equals straight H space cos space straight delta space space ang space straight V apostrophe equals straight V so space angle space of space dip space in space straight a space vertical space plane space making space an space angle space straight delta space with space magnetic space meridian. tan space straight delta apostrophe equals fraction numerator straight V apostrophe over denominator straight H apostrophe end fraction equals fraction numerator straight V over denominator Hcos space straight theta end fraction equals fraction numerator tan space straight delta over denominator cos space straight theta end fraction Here comma space straight delta space is space true space value space of space dip space and space straight delta apostrophe space is space apparent space value space of space dip. For space straight a space vertical space palne space other space than space magnetic space meridian comma space straight theta space greater than space 0 degree comma space cos space straight theta space less than space 1 therefore space straight delta apostrophe space greater than space straight delta space straight i. straight e. space angle space of space dip space increases. When space straight theta space equals space 90 degree comma space tan space straight delta space equals space fraction numerator tan space straight delta over denominator cos space 90 degree end fraction equals infinity therefore space straight delta apostrophe space equals space 90 degree space which space is space in space plane space perpendicular space to space magnetic space meridian comma space dip space needle space will space stand space vertical. end style    

Answered by Priyanka Kumbhar | 22nd Jan, 2016, 02:13: PM