a wire whose resistance is 80 ohm is cut into 3 pieces of equal lengths which r then arranged in parallel.calculate d resistance of d combination,.

As answered previously...


 The resistance of 80 ohm is cut into three pieces. 

 We know, resistance, R = ρL/A 

 ρ is resistivity, L is the length, A is the area of cross-section of the wire. When it is cut into three equal pieces, ρ and A remains constant but L changes. 

 Since, resistance is directly proportional to length. So, if the length becomes L/3 the resistance also becomes R/3. Thus, the resistance of each piece is 80/3 ohm. Now, we have three such pieces connected in parallel. The equivalent resistance of the combination is, 

 1/R  eq  = 1/(80/3) + 1/(80/3) + 1/(80/3) 

 => 1/R  eq  = 9/80 

 => R  eq  = 80/9 = 8.88 ohm 

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