Which of the following will change the strength of a magnetic field? 1.increase speed
2.change the amount of electric current
3.remove atoms
4.it is always the same

2. change the amount of electric current

beta is electron from nucleus

something from nucleus has changed, but charge must be same for cons of charge

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.