Positive and Negative
If for example a positive charge is moving in a positive x direction when it enters a magnetic field and then starts to describe a circle in an anticlockwise direction (in the xy plane), by using the right hand rule I would say that the magnetic field would be in the positive z direction... Would you agree?No. Using the right hand rule to compute for a postive charge moving in the +x direction in a magnetic field in the +z direction I get an initial force in the +y direction--which means clockwise circle. (Viewed from above the x-y plane, where z > 0.)
Now if a negative charge were to enter the same field and describes the same anticlockwise circle, how do I apply the right hand rule in this situation? Would I simple say, ok for a positive charge the direction of the magnetic field was in the z direction, so for a negative charge, the direction must be in the -z direction?I think you have your directions mixed up in this case, but your idea is correct: To get the same direction of force on a negative charge, the magnetic field must be opposite to what it was for the positive charge.A neutral atom or group of atoms becomes an ion by gaining or losing one or more electrons or protons. Since the electron and proton have equal but opposite unit charges, the charge of an ion is always expressed as a whole number of unit charges and is either positive or negative. A simple ion consists of only one charged atom; a complex ion consists of an aggregate of atoms with a net charge. If an atom or group loses electrons or gains protons, it will have a net positive charge and is called a cation. If an atom or group gains electrons or loses protons, it will have a net negative charge and is called an anion.
Since ordinary matter is electrically neutral, ions normally exist as groups of cations and anions such that the sum total of positive and negative charges is zero. In common table salt, or sodium chloride, NaCl, the sodium cations, Na+, are neutralized by chlorine anions, Cl-. In the salt sodium carbonate, Na2CO3, two sodium cations are needed to neutralize each carbonate anion, CO3-2, because its charge is twice that of the sodium ion.
If for example a positive charge is moving in a positive x direction when it enters a magnetic field and then starts to describe a circle in an anticlockwise direction (in the xy plane), by using the right hand rule I would say that the magnetic field would be in the positive z direction... Would you agree?No. Using the right hand rule to compute for a postive charge moving in the +x direction in a magnetic field in the +z direction I get an initial force in the +y direction--which means clockwise circle. (Viewed from above the x-y plane, where z > 0.)
Now if a negative charge were to enter the same field and describes the same anticlockwise circle, how do I apply the right hand rule in this situation? Would I simple say, ok for a positive charge the direction of the magnetic field was in the z direction, so for a negative charge, the direction must be in the -z direction?I think you have your directions mixed up in this case, but your idea is correct: To get the same direction of force on a negative charge, the magnetic field must be opposite to what it was for the positive charge.A neutral atom or group of atoms becomes an ion by gaining or losing one or more electrons or protons. Since the electron and proton have equal but opposite unit charges, the charge of an ion is always expressed as a whole number of unit charges and is either positive or negative. A simple ion consists of only one charged atom; a complex ion consists of an aggregate of atoms with a net charge. If an atom or group loses electrons or gains protons, it will have a net positive charge and is called a cation. If an atom or group gains electrons or loses protons, it will have a net negative charge and is called an anion.
Since ordinary matter is electrically neutral, ions normally exist as groups of cations and anions such that the sum total of positive and negative charges is zero. In common table salt, or sodium chloride, NaCl, the sodium cations, Na+, are neutralized by chlorine anions, Cl-. In the salt sodium carbonate, Na2CO3, two sodium cations are needed to neutralize each carbonate anion, CO3-2, because its charge is twice that of the sodium ion.
