The force on a wire carrying 8.75 a is a maximum of 1.28 n when placed between the pole faces of a magnet

if the pole faces are 55.5 cm in diameter, what is the approximate strength of the magnetic field?

In a particular chemical reaction, the energy of the reactants is 30 kj and the energy of the products is 5 kj. 
 the maximum energy of the system is 40 kj. sketch a potential energy diagram for this reaction. make sure to label the energy of the reactants, the energy of the products, the activation energy, and the enthalpy change for the reaction.