A set of n equal resistors of value R each are connected in series to battery of emf E and internal resistance R. Current drawn is I. Now n resistors are connected in parallel to same battery; current becomes 10I. Find n:
Options

Question

A set of n equal resistors of value R each are connected in series to battery of emf E and internal resistance R. Current drawn is I. Now n resistors are connected in parallel to same battery; current becomes 10I. Find n:

Options

G1 Physics · Accepted Answer

Step 1: For n in series with r = R, Iₛ = E/[(n+1)R]. Step 2: For n in parallel, Rₚ = R/n, so Iₚ = E/[R+R/n] = nE/[(n+1)R]. Step 3: Iₚ/Iₛ = n = 10. Hence n = 10 (option C).