The intensity of the magnetic force F experienced by a charge q moving with speed v in a magnetic field of intensity B is equal to

where

is the angle between the directions of v and B.
1) Re-arranging the previous formula, we can calculate the value of the magnetic field intensity. The charge is

. In this case, v and B are perpendicular, so

, therefore we have:

2) In this second case, the angle between v and B is

. The charge is now

, and the magnetic field is the one we found in the previous part, B=2.8 T, so we can find the intensity of the force experienced by this second charge:
It would be B since it starts with the solar energy which is converted to electricity with the solar panels, which then creates mechanical energy for the fans blades to move and sound for the radio.
Hope that helps :)
16.1=4.472222 i hope this helps!!
The answer is D. Isotopes.
Hope that helped.