✓ Board-verified
Science · 2026 · 3 marks
CBSE 2026 · Region 5 · Set 3 · Q36
An object of height 6 cm is placed at a distance of 30 cm from the optical centre of a concave lens of focal length 15 cm. Use lens formula to…
An object of height $\displaystyle 6$ cm is placed at a distance of $\displaystyle 30$ cm from the optical centre of a concave lens of focal length $\displaystyle 15$ cm. Use lens formula to determine :
(a)
The distance of image from the optical centre.
(b)
The height of the image formed.
Marking-scheme solution
(a)
Height of object \(\displaystyle =6.0 \mathrm{~cm}\)
\[\begin{aligned}
& u=-30 \mathrm{~cm} \\
& f=-15 \mathrm{~cm} \\
& \frac{1}{\mathrm{v}}-\frac{1}{u}=\frac{1}{f} \\
& \frac{1}{\mathrm{v}}=\frac{1}{f}+\frac{1}{u} \\
& \frac{1}{\mathrm{v}}=\frac{1}{-15}+\frac{1}{-30}
\end{aligned}
\]
\[\mathrm{v}=-10 \mathrm{~cm}
\]
(b) \[\begin{aligned}
m & =\frac{\mathrm{v}}{u} \\
m & =\frac{-10}{-30} \\
m & =\frac{1}{3}
\end{aligned}
\]
All Light - Reflection and Refraction questions2026 question paperNCERT solutions: Light - Reflection and RefractionPractice Light - Reflection and Refraction →
More from Light - Reflection and Refraction
- With the help of above given ray diagram, calculate the angle of refraction. Given that the refractive index of Medium 2 with respect to Medium 1 is…2026
- A student wants to obtain an erect image of an object using a concave mirror of 10 cm focal length. What will be the distance of the object from…2023
- An object is kept at a distance of 1m from a lens of power+2D: (i) Identify the type of lens. (ii) Calculate its focal length and distance of the…2023
- If the absolute refractive indices of two media X and Y are 6/5 and 4/3 respectively, then the refractive index of Y with respect to X will be:2025
- A student wants to project the image of a candle flame on a screen 60 cm in front of a mirror by keeping the candle at a distance of 15 cm from its…2023
- An object is placed in front of a concave mirror of focal length 12 cm. If distance of the object from the pole of the mirror is 8 cm, then use…2024
- (i) "In refraction of light through a rectangular glass slab, the emergent ray is always parallel to the direction of the incident ray." Why? Explain…2025
- The above ray diagram is to show image formation by a reflecting telescope. Reflecting telescope revolutionized our way of looking into the sky.…2026
CBSE Class 10 Science past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.