| |
|
|
| |
 |
| Numerical - 05 |
|
| 05. A telephone cable at a place has four long straight horizontal wires carrying a current of 1 ampere in the same direction east to west. The Earth's magnetic field at the place is 0.39 gauss, and the angle of dip is 35o. The magnetic declination is nearly zero. What are the resultant magnetic fields at points 4.0 cm below, and above the cable? |
| |
| Suggested solution: |
| |
 |
| |
| = 0.39 x 0.82 gauss = 0.32 gauss |
| |
 |
| |
| = 0.39 x 0.57 gauss = 0.22 gauss |
| |
| The magnetic field at a distance of 4 cm is given by |
| |
 |
| |
| Below the wire |
| |
| Resultant horizontal magnetic field, |
| |
| RH=(0.32-0.20)gauss = 0.22 gauss |
| |
| Vertical field, Rv= 0.22 gauss |
| |
| Resultant field, |
| |
 |
| |
 |
| |
 |
| |
 |
| |
| Above the wire |
| |
| Resultant horizontal magnetic field, RH = (0.32+0.20) gauss |
| |
| = 0.52 gauss. |
| |
| Vertical field, |
| |
| Rv = 0 .22 gauss |
| |
 |
| |
 |
| |
 |
| |
 |
| |
|
|
| |
|
|
| |
|
|
|
|
|
