Q:
      
      
         
            
Two metallic wires made from copper have same length but the radius of wire 1 is half of that of wire 2. The resistance of wire 1 is R. If both the wires are joined together in series, the total resistance becomes
 
         
       
      
      
      
          
      
      
          Answer & Explanation
         Answer: C) 5R/4         
         
Explanation: So, resistance of Wire 2 is R/4 as radius is half of wire 1, so area would be 4 times of wire 1.
Now for resistance in series. R= R1 + R2.
Therefore, Final R= R + R/4 = 5R/4
 
       
      
      
      
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