As we know, force per unit length between two parallel straight wires is given by, F=2πdμ0i1i2.
Therefore, required ratio
F2F1=2π(25×10−2)μ0(20)22π(5×10−2)μ0(10)2=81
⇒F2=8F1
JEE Main 2023 — Physics Electromagnetism
Two long straight wires P and Q carrying equal current 10A each were kept parallel to each other at 5cm distance. Magnitude of magnetic force experienced by 10cm length of wire P is F1. If distance between wires is halved and currents on them are doubled, force F2 on 10cm length of wire P will be:
Held on 24 Jan 2023 · Verified 6 Jul 2026.
8F1
10F1
8F1
10F1
Sign in to track your attempts and accuracy.
Sign in to keep a private note on this question. Nothing you write is ever public.
A circular loop of radius $20\text{ cm}$ and resistance $2\ \Omega$ is placed in a time varying magnetic field $\vec{B} = (2t^2 + 2t + 3)\text{ T}$. At $t = 0$, for the plane of the loop being perpendicular to the magnetic field and, the induced current in the loop at $t = 3\text{ s}$ is $\dfrac{\alpha}{50}\text{ A}$. The value of $\alpha$ is _______. (Take $\pi = 22/7$)
A particle having charge $10^{-9}$ C moving in $x$-$y$ plane in fields of $0.4\hat{j}$ N/C and $4 \times 10^{-3} \hat{k}$ T experiences a force of $(4\hat{i} + 2\hat{j}) \times 10^{-10}$ N. The velocity of the particle at that instant is _______ m/s.
A current carrying solenoid is placed vertically and a particle of mass $m$ with charge $Q$ is released from rest. The particle moves along the axis of solenoid. If $g$ is acceleration due to gravity then the acceleration (a) of the charged particle will satisfy :
Refer to the figure given below. The values of $I_1$, $I_2$ and $I_3$ are __________. 
Identify the correct statements : A. Electrostatic field lines form closed loops. B. The electric field lines point radially outward when charge is greater than zero. C. The Gauss - Law is valid only for inverse - square force. D. The workdone in moving a charged particle in a static electric field around a closed path is zero. E. The motion of a particle under Coulomb's force must take place in a plane. Choose the correct answer from the options given below :
Work through every JEE Main Electromagnetism PYQ, year by year.