| |
|
|
| |
 |
| Numerical 15 |
 |
| 15. Two straight wires A and B of lengths 10m and 12m carrying currents of 4.0A and 6.0A respectively in opposite directions lie parallel to each other at a distance of 3.0cm. Estimate the force on a 15cm section of the wire B near its centre. |
| |
| Suggested solution: |
| |
| The ratio of the length of the wires to the separation between them is large (more than 300). Therefore, one can estimate the approximate force on a section of either of the two wires (near their centres) by using the exact result for force per unit length for two infinitely long wires carrying currents I1 and I2. |
| |
 |
| |
| Force per unit length |
| |
 |
| |
| Force on 15cm section of wire B (near it's centre) |
| |
| = 1.6 x 10-4 x 0.15 N |
| |
| = 2.4 x 10-5 N |
| |
|
|
| |
|
|
| |
|
|
|
|
|
Moving Charges and Magnetism
|
|
|