CBSE 2025 · Region 1 · Set 2 · Q23 · 2 marks
An object is placed at a distance of $\displaystyle 30$ cm in front of a concave mirror of focal length $\displaystyle 20$ cm . Use mirror formula to determine the position of the image formed in this case.
Marking-scheme solution
\[\begin{aligned}
& \begin{array}{l}
\mathrm{f}=-20 \mathrm{~cm} ; \mathrm{u}=-30 \mathrm{~cm} \\
\frac{1}{f}=\frac{1}{v}+\frac{1}{u}
\end{array} \\
& \frac{1}{v}=\frac{1}{-20}-\frac{1}{-30} \\
& \frac{1}{v}=\frac{1}{-20}+\frac{1}{30}
\end{aligned}
\] Position of image is $\displaystyle 60$ cm in front of the mirror.
Light - Reflection and RefractionSign Convention, Mirror Formula and MagnificationApplyvery_short_answereasy
More from Light - Reflection and Refraction
- (i) "In refraction of light through a rectangular glass slab, the emergent ray is always parallel to the…2025 · asked 3×
- Draw ray diagrams to show the nature, position and relative size of the image formed by a convex mirror when…2025 · asked 3×
- Out of the two lenses, one concave and the other convex, state which one will diverge a parallel beam of…2025 · asked 3×
- The power of a lens is -0.25 D. Based on this information, find out The type of lens and its focal length.…2025 · asked 3×
- An optical device 'X' is placed obliquely in the path of a narrow parallel beam of light. If the emergent…2025 · asked 3×
- Study the figure in which the path of a ray of light going from Medium 1 to Medium 2 is shown. Out of the two…2025 · asked 3×
- To get an image of magnification -1 on a screen using a lens of focal length 20 cm, the object distance must…2025 · asked 3×
- In order to obtain large images of the teeth of patients, the dentist holds the concave mirror in such a…2025 · asked 3×
CBSE Class 10 Science past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.