Doubtclip is an AI tutor that turns any homework or exam doubt into a step-by-step whiteboard video lesson with diagrams, formulas, and voice explanation.

Which subjects and exams does it support?

It supports Physics, Chemistry, Mathematics/Calculus and related STEM doubts for school boards, JEE, NEET, and global high-school / undergrad practice.

How do I get a video solution?

Upload a photo of the question or paste the text, sign in, and Doubtclip generates a whiteboard-style explanation video you can watch and share.

Is Doubtclip available worldwide?

Yes. Doubtclip is a web app for students globally. Lessons are available in English and Hinglish.

Current Electricity

JEE Main level, numerical answer, medium

136 of 380

Question 136 of 380

First, a set of $n$ equal resistors of $10\Omega$ each are connected in series to a battery of E.M.F. $20V$ and internal resistance $10\Omega .$ 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 $20$ times, then the value of $n$ is ___________.

Show answer and solution

Answer: 20

When the resistances of each

10\Omega

â€‹ are connected in series and parallel then,

{R}_{s}=10n

, and

{R}_{p}=\dfrac{10}{n}

. Given,

{i}_{p}=20{i}_{s}

\Rightarrow \dfrac{20}{\left(\dfrac{10}{n}+10\right)}=20\left(\dfrac{20}{10n+10}\right)\Rightarrow \dfrac{20n}{10+10n}=20\left(\dfrac{20}{10n+10}\right)

\Rightarrow n=20

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.

See it move: Circuit builder simulationDrag the sliders and watch the numbers in this question change.Revise Current Electricity firstFormula sheet, solved examples and the traps students fall into.

More Physics practice

JEE Main Physics practice question on Current Electricity (Combination of Resistances), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.