Force due to Magnetic Field Biot-Savart Law

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A current carrying conductor experiences a **force when placed in a magnetic field**.
The **direction of force is reversed when the direction of current in the conductor is reversed**.
The force acting on the current-carrying conductor can be changed by **changing
the direction of the magnetic field**.

## Flemings Left Hand Rule

According to this rule, extend the thumb, forefinger, and the middle finger of the left hand in such a way that all the three are mutually perpendicular to each another. If the**forefinger points in the direction
of the magnetic field** and the **middle finger in the direction of the
current**, then, the **thumb points in the direction of the force exerted
on the conductor**.

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## Biot-Savart Law

According to this rule, extend the thumb, forefinger, and the middle finger of the left hand in such a way that all the three are mutually perpendicular to each another. If the

Consider a small piece of wire of length ds carrying a current I. This defines a vector ds that points in the direction of the current. The magnetic field dB set up by this piece of current-carrying wire at a point a distance r away is:

Proportional to**1/r^2** .

Proportional to**I, the current, and ds, the length of the wire** .

In a direction**perpendicular to both ds and r**, the vector from the wire to the point

Proportional to**sinx** , where x is the angle between ds and r

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Proportional to

Proportional to

In a direction

Proportional to