C the correct but not sure?
        
             
        
        
        
Answer:
The magnetic field strength and the electrons' energy are 0.077 T and 0.8906 eV.
Explanation:
Given that,
Diameter = 2.62 mm
Frequency = 2.15 GHz
(A). We need to calculate the magnetic field strength
Using formula of the magnetic field strength

Where, f = frequency
e = charge of electron
Put the value into the formula


(B). We need to calculate the energy of electron
Using formula of energy



The energy in eV



Hence, The magnetic field strength and the electrons' energy are 0.077 T and 0.8906 eV.
 
        
             
        
        
        
You need to know the specific heat capacity of air.
Then energy needed = 0.005 x sp.heat.cap x 10
        
             
        
        
        
The kinetic energy of the small ball before the collision is
                             KE  =  (1/2) (mass) (speed)²
                                     = (1/2) (2 kg) (1.5 m/s)
                                     =    (1 kg)  (2.25 m²/s²)
                                     =        2.25 joules.
Now is a good time to review the Law of Conservation of Energy:
                     Energy is never created or destroyed.  
                     If it seems that some energy disappeared, 
                     it actually had to go somewhere.
                     And if it seems like some energy magically appeared, 
                     it actually had to come from somewhere.
The small ball has 2.25 joules of kinetic energy before the collision.
If the small ball doesn't have a jet engine on it or a hamster inside,
and does not stop briefly to eat spinach, then there won't be any 
more kinetic energy than that after the collision.  The large ball 
and the small ball will just have to share the same 2.25 joules.