NEET Questions Solved


Two wires of equal diameters, of resistivities ρ1 and ρ2 and lengths l1 and l2, respectively, are joined in series. The equivalent resistivity of the combination is 

(1) ρ1l1+ρ2l2l1+l2

(2) ρ1l2+ρ2l1l1l2

(3) ρ1l2+ρ2l1l1+l2

(4) ρ1l1ρ2l2l1l2 

(1) R1=ρ1l1A​ and R2=ρ2l2A.

In series Req=R1+R2

ρeq.(l1+l2)A=ρ1l1A+ρ2l2A  ρeq=ρ1l1+ρ2l2l1+l2.

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