AP EAMCET202023 Sep 2020Morning ShiftPhysicsCurrent ElectricityActual
Two wires of equal diameters, lengths l 1 , l 2 and having resistivities S 1 , S 2 respectively are joined in series. The equivalent resistivity of the combination is ____
Options
- As 1 l 1 + s 2 l 2 l 1 + l 2
- Bs 1 l 2 + s 2 l 1 l 1 - l 2
- Cs 1 l 2 + s 2 l 1 l 1 + l 2
- Ds 1 l 2 - s 2 l 1 l 1 - l 2
Correct answer
A. s 1 l 1 + s 2 l 2 l 1 + l 2
Step-by-step solution
Equivalent resistance for series combination is given by R = R 1 + R 2 ⇒ S l total A = S 1 l 1 A + S 2 l 2 A   ∴     l total = l 1 + l 2 ⇒ S = S 1 l 1 + S 2 l 2 l 1 + l 1