Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
A body of mass $M$ and charge $q$ is connected to a spring of spring constant $k$. It is oscillating along $\mathrm{x}$-direction about its equilibrium position, taken to be at $x=0$, with an amplitude $A$. An electric field $E$ is applied along the $\mathrm{x}$-direction. Which of the following statements is correct?
PhysicsElectrostaticsJEE MainJEE Main 2018 (15 Apr Shift 1 Online)
Options:
  • A
    The total energy of the system is
    $$
    \frac{1}{2} m \omega^2 A^2+\frac{1}{2} \frac{q^2 E^2}{k}
    $$
  • B
    The new equilibrium position is at a distance: $\frac{2 q E}{k}$ from $x=0$
  • C
    The new equilibrium position is at a distance: $\frac{q E}{2 k}$ from $\mathrm{x}=0$
  • D
    The total energy of the system is $\frac{1}{2} m \omega^2 A^2-\frac{1}{2} \frac{q^2 E^2}{k}$
Solution:
2381 Upvotes Verified Answer
The correct answer is:
The total energy of the system is
$$
\frac{1}{2} m \omega^2 A^2+\frac{1}{2} \frac{q^2 E^2}{k}
$$
Equilibrium position will shift to point where resultant force $=0$
$$
\mathrm{kx}_{\text {eq }}=\mathrm{qE} \Rightarrow \mathrm{x}_{\text {eq }}=\frac{\mathrm{qE}}{\mathrm{k}}
$$
Total energy $=\frac{1}{2} \mathrm{~m} \omega^2 \mathrm{~A}^2+\frac{1}{2} \mathrm{kx}_{\text {eq }}^2$
Total energy $=\frac{1}{2} m \omega^2 A^2+\frac{1}{2} \frac{q^2 E^2}{k}$

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.