Volumetric flasks are most accurate
 
        
                    
             
        
        
        
Answer:

Explanation:
Let the sphere is uniformly charge to radius "r" and due to this charged sphere the electric potential on its surface is given as

now we can say that


now electric potential is given as


now work done to bring a small charge from infinite to the surface of this sphere is given as


here we know that

now the total energy of the sphere is given as




  
        
             
        
        
        
Answer:
It has 5 I hope this helps you 
 
        
             
        
        
        
Answer:
The magnetic field strength inside the solenoid is  .
.
Explanation:
Given that,
Radius = 2.0 mm
Length = 5.0 cm
Current = 2.0 A
Number of turns = 100
(a). We need to calculate the magnetic field strength inside the solenoid
Using formula of the magnetic field strength 
Using Ampere's Law

Where, N = Number of turns
I = current 
l = length
Put the value into the formula


(b). We draw the diagram 
Hence, The magnetic field strength inside the solenoid is  .
.
 
        
             
        
        
        
Answer:
The velocity of the tennis ball is 4.52 m/s.
Explanation:
Given that,
The distance covered by ball, d = 9.5 meters (due south)
Time, t = 2.1 sec
Let v is the velocity of the tennis ball. We know that the velocity of an object is given by the total distance covered divided by total time taken. It is given by :

So, the velocity of the tennis ball is 4.52 m/s. Hence, this is the required solution.