A flim of water if found between two straight parallel wires of length 0.10m each separated by 5 xx 10^(-3)m. If their separation is increased by 1 xx 10^(-3)m, while maintaining their parallelism, how much work will have to be done? (S.T. of water is 7.2 xx 10^(-2) Nm^(-2)).

A flim of water if found between two straight parallel wires of length

1.	A flim of water if found between two straight parallel wires of length 0.10m each separated by 5 xx 10^(-3)m. If their separation is increased by 1 xx 10^(-3)m, while maintaining their parallelism, how much work will have to be done? (S.T. of water is 7.2 xx 10^(-2) Nm^(-2)).
Answer» Solution :GIVEN `d=5 xx 10^(-3) m, l=0.10m` `d=6 xx 10^(-3)m, l=0.10m` `A=ld =0.10 xx 5 xx 10^(-3) =5 xx 10^(-4)m^(2)` `A.=ld. =0.1 xx 6 xx 10^(-3) =6 xx 10^(-4) m^(2)` `DeltaA=1 xx 10^(-4) m^(2)`. Net AREA `=2DeltaA=2 xx 10^(-4)m^(2)` Work done `=(T)(2DeltaA)=0.072 xx 2 xx 1 xx 10^(-4)=0.144 xx 10^(-4) =1.44 xx 10^(-5)J`