Chapter 20, Problem 12P

Find the direction of the force on a negative charge for each diagram shown in Fig. 20-52 0_:where (green) is the velocity of the charge and B (blue) is the direction of the magnetic field. (& means the vector points inward. © means it points outward, toward you.)

To determine

Part (a) To Determine:

Direction of force on the negative charge due to given direction magnetic field and velocity

Answer to Problem 12P

Solution:

No force

Explanation of Solution

Since direction of $\overrightarrow{v}$ and $\overrightarrow{B}$ are in same line but in opposite direction ($\theta ={180}^0$)so force acting on charge particle is $F=qvB\mathrm{Sin}\theta$$=0$.No force acts on charge particle.

To determine

Part (b)To determine:

Direction of force on a negative charge due to given direction of magnetic field and velocity

Answer to Problem 12P

Solution:

Downward

Explanation of Solution

Since magnetic field is in outward direction and according to given direction of velocity using Fleming’s Left-Hand Rule direction of force comes in downward direction.

To determine

Part (c)To determine:

Direction of force on a charge particle

Answer to Problem 12P

Solution:

Upwards

Explanation of Solution

Since velocity in inwards to plane and with respect to direction of given magnetic field using Fleming’s Left-Hand Rule direction of force is in Upwards direction.

To determine

Part (d)To determine:

Direction of force on a negative charge particle

Answer to Problem 12P

Solution:

Inwards into the paper

Explanation of Solution

Since direction of velocity and magnetic field is perpendicular to each other represented by x axis and y axis respectively. According to the relation,

$\overrightarrow{F}=q(\overrightarrow{v}\times \overrightarrow{B})$

Direction of force on a negative charge particle can be identified by using this relation,

$\overrightarrow{F}=-q(\widehat{i}\times \widehat{j})=-\widehat{k}$

This $-\widehat{k}$ indicates the inwards direction perpendicular to the plane containing $\overrightarrow{v}\&\overrightarrow{B}$

To determine

Part (e)To determine:

To determine the direction of force on a negative charge particle.

Answer to Problem 12P

Solution:

Left

Explanation of Solution

Since magnetic field is inwards direction and velocity is in downward direction so direction of force due to negative charge particle is in left side of $\overrightarrow{B}$.

To determine

Part (f)To determine:

To determine the direction of force on a negative charge particle.

Answer to Problem 12P

Solution:

Left

Explanation of Solution

Since velocity is in outward direction and magnetic field is in downward direction so direction of force due to negative charge particle is in left side of $\overrightarrow{v}$.