JEE Main 2024 — 27 January, Shift 2 — Question 52

$\mathrm{f}_{\mathrm{c}}=\frac{\mathrm{v}}{4 \ell_{1}} \quad \mathrm{f}_{\mathrm{o}}=\frac{\mathrm{v}}{2 \ell_{2}}$

$\left|\mathrm{f}_{\mathrm{c}}-\mathrm{f}_{0}\right|=7$

$\frac{v}{4 \times 150}-\frac{v}{2 \times 350}=7$

$\frac{\mathrm{v}}{600 \mathrm{~cm}}-\frac{\mathrm{v}}{700 \mathrm{~cm}}=7$

$\frac{v}{6 m}-\frac{v}{7 m}=7$

$\mathrm{v}\left(\frac{1}{42}\right)=7$

$\mathrm{v}=42 \times 7$

$=294 \mathrm{~m} / \mathrm{s}$