Answer:
(a). The speed of electron is  .
.
(b). The radius of electron is 
Explanation:
Given that,
Length = 2.5 cm
Distance = 6.0 mm
Magnetic field = 2.1 T
Potential difference = 700 V
(a). We need to calculate the electron's speed
Using formula of speed

Put the value into the formula



(b). We need to calculate the radius of electron
Using formula of centripetal force


Where,
m = mass of electron
v = speed of electron
r = radius
q = charge of electron
B = magnetic field
Put the value into the formula



Hence, (a). The speed of electron is  .
.
(b). The radius of electron is 4.2 cm
 
        
             
        
        
        
Answer:
Explanation:
Given
Radius of A is twice of B i.e.

Also Potential of both sphere is same 


thus 




(b)Ratio of 
Electric Field is given by 
thus  ----1
----1
 ----2
----2
Divide 2 by 1


 
        
             
        
        
        
In empty space, there's nothing to exert force on the ball after it leaves 
her hand.  It sails away in a straight line, at constant speed of 13 m/s.  
If it doesn't sail too close to a planet, a star, an asteroid, or a moon, it 
may travel 6 billion light years and still be moving at 13 m/s.
        
                    
             
        
        
        
Since the fourmula is mass/volume=density multiplying the density and volume yields the mass which is  <span>0.80522 grams.</span>