Complete Question 
 A 10-cm-long thin glass rod uniformly charged to 8.00 nC and a 10-cm
long thin plastic rod uniformly charged to -8.00 nC are placed side by
 side, 4.20 cm apart. What are the electric field strengths E_1 to E_3 at 
distances 1.0 cm, 2.0 cm, and 3.0 cm from the glass rod along the line 
connecting the midpoints of the two rods
a.) Specify the electric field strength E1
b.) Specify the electric field strength E2
c.) Specify the electric field strength E3
Answer:
               
              
                
 
Explanation:
   From the question we are told that 
           The length of the thin glass is  
           The  charge on the glass rod is  
            The length of the plastic rod is  
              The charge on the  plastic rod is 
            The distance between the materials  is 
           The various distances to obtain electric field of are 
                                                                                                 
                                                                                                  
The objective of the solution is to obtain the electric field  at distance
 at distance  from the glass rod  along the line connecting its mid point
  from the glass rod  along the line connecting its mid point  
    Generally electric field of a charge rod at a distance of r the line dividing the rod  into half  is mathematically represented as 
                               
For the   
 
 The electric filed by the positively charge glass rod on the left side of the dividing line is mathematically represented as 
                                
 The electric filed by the positively charge glass rod on the right  side of the dividing line is mathematically represented as  
                             
The net electric field is,
             
                     
 Where k is  know as the coulomb's constant  with a constant value of 
                   
            
                            
                            
For the   
 
            The electric filed by the positively charge glass rod on the left side of the dividing line is mathematically represented as 
                                
 The electric filed by the positively charge glass rod on the right  side of the dividing line is mathematically represented as  
                             
The net electric field is,
             
                     
 Where k is  know as the coulomb's constant  with a constant value of 
                   
             
 
             
              
For the   
 
            The electric filed by the positively charge glass rod on the left side of the dividing line is mathematically represented as 
                                
 The electric filed by the positively charge glass rod on the right  side of the dividing line is mathematically represented as  
                             
The net electric field is,
             
                     
 Where k is  know as the coulomb's constant  with a constant value of 
                   
            
         
       