MENU

If two charges +4e and +e are at a distance x apart, then at what distance charge q

If Two Charges 4e And E Are At A Distance Physics Question

If two charges +4e and +e are at a distance x apart, then at what distance charge q must be placed from +e, so that it is in equilibrium?

Options

(a) x/2
(b) x/3
(c) x/6
(d) 2x/3

Correct Answer:

x/3

Explanation:

For equilibrium of q, |F₁| = |F₂|

(1 / 4πε₀).(qq₁ / x₁) = (1 / 4πε₀).(qq₂ / x₂)

x₂ = x / √[(q₁/q₂) + 1] = x / √[(4e/e) + 1] = x / 3

Related Questions:

  1. If force is proportional to square of velocity, then the dimension of proportionality
  2. Four blocks of same mass connected by cords are pulled by a force F
  3. Two bodies of mass 1 kg and 3 kg have positive vectors i + 2j + k and -3i -2j + k
  4. If force(F),velocity(v) and time(T) are taken as units, then the dimensions of mass are
  5. The ratio of speed of an electron in ground state in Bohr’s first orbit of hydrogen atom

Topics: Electrostatics (146)
Subject: Physics (2479)

Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score

18000+ students are using NEETLab to improve their score. What about you?

Solve Previous Year MCQs, Mock Tests, Topicwise Practice Tests, Identify Weak Topics, Formula Flash cards and much more is available in NEETLab Android App to improve your NEET score.

NEETLab Mobile App

Share this page with your friends

1 Comment on If two charges +4e and +e are at a distance x apart, then at what distance charge q

  1. Let q be r distant from e .

    e ……q…….4e
    _r___
    ______x___

    Force on q due to e

    = k qe / r^2

    Force on q due to 4e

    = k q4e / ( x – r )^2

    For it to be in equibrium :

    The forces must be equal and opposite .

    kqe/r^2 = k4eq/(x-r)^2

    => 1/r^2 = 4/(x-r)^2

    => x^2 + r^2 -2xr = 4r^2

    => 3r^2 + 2xr -x^2 = 0

    => 3r^2 + 3xr – xr – x^2 = 0

    => 3r ( r + x ) -x ( r + x ) = 0

    => ( 3r-x ) ( r + x ) = 0

    => r = -x or r = x/3

    Since distance is non-negative

    r = x/3 should be the answer .

Leave a Reply

Your email address will not be published.


*