Q1 of 92 Page 249

The magnetic field a the origin due to a current element placed at a position is


According to Biot-Savart law:
The magnetic field due to a current element is given as
Where,

i is the current,


is the length element vector,


is the vector joining the required point and the length element,


μ0 is the permeability of vacuum and μ0 = 4π × 10-7 TmA-1.
Also, by vector properties: A× B = -(B× A)
Thus,
 Thus, options (A) and (B) are the correct options

More from this chapter

All 92 →
11

Two parallel, long wires carry currents i1 and i2 with i1> i2. When the currents are in the same direction, the magnetic field at a point midway between the wires is 10 μT. If the direction of i2 is reversed, the field becomes 30 μT. The ratio i1/i2 is

 12

Consider a long, straight wire of cross-sectional area A carrying a current i. Let there be n free electrons per unit volume. An observer places himself on a trolley moving in the direction opposite to the current with a speed and separated from the wire by a distance r. The magnetic field seen by the observer is very nearly.

 2

Consider three quantities x = E/B, y = and . Here, ℓ is the length of a wire, C is a capacitance and R is a resistance. All other symbols have standard meanings.

 3

A long, straight wire carries a current along the z-axis. One can find two points in the x-y plane such that