JEE Main 2022 · 24 Jun · Shift 2 · Physics Q41

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PhysicsSingle correct+4 / -1Question 41 of 90

Potential energy as a function of $r$ is given by $U=\dfrac A{r^{10}}-\dfrac B{r^5}$ , where r is the interatomic distance. A and B are positive constants. The equilibrium distance between the two atoms will be :

\left(\dfrac AB\right)^{\frac15}

\left(\dfrac BA\right)^{\frac15}

\left(\dfrac{2A}B\right)^{\frac15}

\left(\dfrac B{2A}\right)^{\frac15}

Answer and worked solution

Official answer: C

Equilibrium where $\dfrac{dU}{dr}=0$ : $-\dfrac{10A}{r^{11}}+\dfrac{5B}{r^6}=0$ .

Solve. $r^5=\dfrac{2A}B$ , so $r=\left(\dfrac{2A}B\right)^{1/5}$ .

(C)

Topics:Potential energy and conservative forces

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JEE Main 2022 · 24 Jun · Shift 2, Physics question 41