Question

a uniform wire when directly connected along a 220 v line produces h heat per second .if the wire is divided into n parts then the heat produced per second will be ?

Answer 1

It is not clear how one of the n segments is connected with the voltage 220V.  So I give two possibilities.

Resistance of a uniform wire of cross sectional area A and length L = R = ρL/A
Power dissipated by a resistance R = P = V² / R = I² R ,    V = 220 V
Heat produced by the wire = power * duration = H = V² T /R = I² R T

1)   When the entire wire of length L is connected across V = 220 V, the it produces a heat energy of H.   In the same configuration, one of the n segments of length L/n has resistance R₁ = R/n.   The current flowing through this segment is same as total current I.

  Hence heat produced in this segment is = I²R₁ = I²(R/n) T =  H/n

2)  When one segment of the n segments is connected across voltage V = 220 V,
    then  heat produced is  =  V² T / R₁ = n V² T / R.
 
       So heat produced in one segment is n times that produced by entire wire.