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### College Physics (Urone)

Book edition 1st Edition
Author(s) Paul Peter Urone
Pages 1272 pages
ISBN 9781938168000

# Make a drawing and use RHR-2 to find the direction of the magnetic field of a current loop in a motor (such as in Figure 22.34). Then show that the direction of the torque on the loop is the same as produced by like poles repelling and unlike poles attracting.

The direction of the magnetic field of a current loop in a motor is out of the paper in the area outside the loop and into paper in the area inside the loop.

See the step by step solution

## Step 1: Right Hand Rule-2

Right-hand-rule-2 (RHR-2) states that if the thumbs point in the direction of the current, the fingers curl in the direction of the field.

## Step 2: Direction of the magnetic field of a current

Using RHR-2, we say that the direction of the magnetic field of a current loop in a motor is out of the paper in the area outside the loop and into paper in the area inside the loop.

Diagrammatic representation of the magnetic field and current in the motor as:

## Step 3: Defining torque

Torque is defined as${}^{\mathfrak{r}=\mathbf{rF}\mathbf{}\mathbf{sin\theta }}$; where r is the distance, F is the applied force, and${}^{\mathrm{\theta }}$ is the angle between r and F.

## Step 5: Direction of the torque on the loop

Here the torque on the loop can rotate in either a clockwise or counter-clockwise manner.

For the first case, torque on the loop is clockwise, which refers to unlike poles attracting.

For the second case, the torque on the loop is counter-clockwise, which refers to similar poles repelling.