Chapter 20, Problem 1OQ

Part (a)

To determine

Force experienced by electric charge at rest when placed in a magnetic field of a magnet.

Solution: Electric charge at rest will not experience any force.

Explanation of Solution

Static Electric charge will not experience any force because according to the Lorentz relation $F=qvB\mathrm{Sin}\alpha$ , ( $\alpha$ is the angle between direction of velocity and direction of magnetic field); if $v=0$ then $F=0$ so it will not experience any force.

Conclusion: An external magnetic field always exerts force of other magnets and charge particles.

Part (b)

To determine

To determine: - Force experienced by moving electric charge when placed in magnetic field of a magnet.

Answer to Problem 1OQ

Solution: - Moving electric charge may or may not experience a force.

Explanation of Solution

Explanation: - Dynamic Electric charge will not experience a force if its direction is parallel or anti-parallel to the direction of magnetic field. And with respect to any other direction it will experience a force.

According to Lorentz relation, $F=qvB\mathrm{Sin}\alpha$

For parallel ( $\alpha =0^{}$ ) , anti-parallel ( $\alpha =180$ ) $\Rightarrow \mathrm{Sin}\alpha =0$

So, $F=0$ .

Conclusion: - An external magnetic field always a force on other magnets and charge particles.

Part (c)

To determine

To Determine: - Force experienced by electric current in a wire when placed in magnetic field.

Answer to Problem 1OQ

Solution: - Electric current in a wire will experience a force.

Explanation of Solution

Explanation: - Electric current in a wire will experience a force because current is only due to moving charges and magnetic field always exerts a force on moving charges so, conductor will also experience a force.

Conclusion: - Every conductor experiences a force given by a relation $F=ilB\mathrm{Sin}\theta$ .

Part (d)

To determine

To Determine: - Force experienced by another magnet when placed in magnetic field of a magnet.

Answer to Problem 1OQ

Solution: - Another magnet will experience a force.

Explanation of Solution

Explanation: - Another magnet always experiences a force because it is a natural property of a magnet, but this force can be repulsive or attractive depending on the nature of poles of a magnet.

Conclusion: - Magnetic force between the magnets is inversely proportional to the distance between them.