What are the signs of the charges on the particles in Figure 22.46?

The term "charged particle" refers to a particle that has an electric charge. It could be an ion, such as a molecule or atom having an excess or shortage of electrons in comparison to protons. It might also be an electron, proton, or another elementary particle, all of which are thought to have the same charge

The right-hand rule is a popular mnemonic for remembering how axes in three-dimensional space are oriented. The fact that the three axes of three-dimensional space have two different orientations gives birth to the majority of the many left-hand and right-hand rules.

For positive charge: Point your right hand's thumb and fingers in the direction of the velocity (${}^{\stackrel{\rightharpoondown }{\mathrm{v}}}$) and magnetic field direction (${}^{\mathbf{B}\mathbf{\text{'}}}$), respectively. The palm then points in the direction of the force on the charged particle (${}^{\stackrel{\mathbf{\rightharpoondown }}{\mathbf{F}}}$) due to the magnetic field.

For positive charge, we see that the direction of force is in the left direction.

For negative charge: The force acting on a negative charge is the polar opposite of the force acting on a positive charge, so it will be in the right direction.

For neutral charge: On a neutral charge, the force will be zero, because there is no charge on it.