A piece of wire of resistances R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R' then the ratio `R/R'` is

Options

A. `1/25`
B. `1/5`
C. 5
D. 25

Explanation

When a wire of resistance R is cut in five equal parts, resistance of each pat `R_1=R/5 Omega` Now, all these pieces are joined in parallel, hence,
`1/R.=1/R_1+1/R_1+....5 time s=5/R_1or R.=R_1/5 =1/5 times R/5 =R/25 therefore R/R.=R/((R//25))=25.]`