First, a set of n equal resistors of 10 Ω each are connected in series to a battery of emf 20 V and internal resistance 10 Ω. A current I is observed…

First, a set of n equal resistors of $\displaystyle 10 \Omega$ each are connected in series to a battery of emf $\displaystyle 20$ V and internal resistance $\displaystyle 10 \Omega$. A current I is observed to flow. Then, the n resistors are connected in parallel to the same battery. It is observed that the current is increased $\displaystyle 20$ times, then the value of n is \_\_\_\_.