JEE Mains · Physics · STD 12 - 9. Ray optics and optical instruments
When an object is kept at a distance of \(30\, cm\) from a concave mirror, the image is formed at a distance of \(10\, cm\) from the mirror. If the object is moved with a speed of \(9\, cms ^{-1}\), the speed (in \(cms ^{-1}\) ) with which image moves at that instant is\(....m/s\)
- A \(1\)
- B \(5\)
- C \(9\)
- D \(13\)
Answer & Solution
Correct Answer
(A) \(1\)
Step-by-step Solution
Detailed explanation
\(\left(\frac{d v}{d t}\right)|=| \frac{v^{2}}{u^{2}}\left|\frac{d u}{d t}\right|\) \(=\left(\frac{10}{30}\right) 2 \times 9=1 m / s\)
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
- If an alpha particle with energy 7.7 MeV is bombarded on a thin gold foil, the closest distance from nucleus it can reach is _________ m.
(Atomic number of gold \(=79\) and \(\frac{1}{4 \pi \epsilon_0}=9 \times 10^9\)in SI units)JEE Mains 2026 Hard - A laser beam has intensity of \( 4.0\times10^{14} W/m^{2} \). The amplitude of magnetic field associated with beam is__________ T. (Take \( \epsilon_{0}=8.85\times10^{-12} C^{2}/Nm^{2} \) and \( c=3\times10^{8} m/s \))JEE Mains 2026 Easy
- In a perfectly inelastic collision, two spheres made of the same material with masses 15 kg and 25 kg , moving in opposite directions with speeds of \(10 m / s\) and \(30 m / s\), respectively, strike each other and stick together. The rise in temperature (in \({ }^{\circ} C\) ), if all the heat produced during the collision is retained by these spheres, is :
(specific heat of sphere material \(31 cal / kg .{ }^{\circ} C\) and \(1 cal =4.2 J)\)JEE Mains 2026 Easy - The planet Mars has two moons, if one of them has a period \(7\, hours,\, 30\, minutes\) and an orbital radius of \(9.0 \times 10^{3}\, {km} .\) Find the mass of Mars. \(\left\{\operatorname{Given} \frac{4 \pi^{2}}{G}=6 \times 10^{11} {N}^{-1} {m}^{-2} {kg}^{2}\right\}\)JEE Mains 2021 Medium
- A displacement current of \(4.0\) A can be set up in the space between two parallel plates of \(6\) \(\mu\)F capacitor. The rate of change of potential difference across the plates of the capacitor is nearly \(\alpha \times 10^6\) V/s. The value of \(\alpha\) is __________.JEE Mains 2026 Easy
- A particle is rotating in a circular path and at any instant its motion can be described as \(\theta = \dfrac{5t^4}{40} - \dfrac{t^3}{3}\). The angular acceleration of the particle after \(10\) seconds is _______ rad/s\(^2\).JEE Mains 2026 Medium
More PYQs from JEE Mains
- Two sides of a parallelogram are along the lines \(4 x+5 y=0\) and \(7 x+2 y=0\). If the equation of one of the diagonals of the parallelogram is \(11 \mathrm{x}+7 \mathrm{y}=9\), then other diagonal passes through the point:JEE Mains 2021 Hard
- If the system of linear equations \(x-2 y+z=-4 \); \(2 x+\alpha y+3 z=5 \); \(3 x-y+\beta z=3\) has infinitely many solutions, then \(12 \alpha+13 \beta\) is equal toJEE Mains 2024 Hard
- The number density of free electrons in copper is nearly \(8 \times 10^{28}\,m ^{-3} . A\) copper wire has its area of cross section \(=2 \times 10^{-6}\,m ^2\) and is carrying a current of \(3.2\,A\). The drift speed of the electrons is \(.....\times 10^{-6}\,ms ^{-1}\).JEE Mains 2023 Easy
- A \(100\,m\) long wire having cross-sectional area \(6.25 \times 10^{-4}\,m ^2\) and Young's modulus is \(10^{10}\,Nm ^{-2}\) is subjected to a load of \(250\,N\), then the elongation in the wire will be :JEE Mains 2023 Easy
- Match List\(-I\) with List\(-II.\)
Choose the correct answer from the options given belowList\(-I\) List\(-II\) \((a)\) Capacitance, \(C\) \((i)\) \({M}^{1} {L}^{1} {T}^{-3} {A}^{-1}\) \((b)\) Permittivity of free space, \(\varepsilon_{0}\) \((ii)\) \({M}^{-1} {L}^{-3} {T}^{4} {A}^{2}\) \((c)\) Permeability of free space, \(\mu_{0}\) \((iii)\) \({M}^{-1} L^{-2} T^{4} A^{2}\) \((d)\) Electric field, \(E\) \((iv)\) \({M}^{1} {L}^{1} {T}^{-2} {A}^{-2}\) JEE Mains 2021 Medium - Which of the following statements is false?JEE Mains 2017 Easy