Ebook wait

The needle of the compass will be deflected to
one side or the other, and will finally come to rest at a certain
angle-let us say 45 deg. The dimensions of the instrument are such
that when the deflection is 45 deg. the current flowing through
the coils upon the ring is 1/2 ampere. The ampere is the unit
chosen to designate the strength of the electric current. For
other angles the value of the current may be found from the
following table:
Angles Degrees Current Amperes
10 .088
20 .182
30 .289
40 .420
45 .500
50 .600
55 .715
60 .865
70 1.375
As the magnetic force that acts upon a magnet needle varies in
different places the values given for the current will not be true
in all parts of the country. The table gives correct values for
the immediate vicinity of Chicago and that part of the United
States lying east of Chicago, and north of the Ohio river. The
results given should be multiplied by 1.3 for places south of the
Ohio river and east of the Mississippi.


Pages:
347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371