✓ Board-verified
Science · 2023 · 3 marks
CBSE 2023 · Region 4 · Set 1 · Q31
The power of a lens is+4D. Find the focal length of this lens. An object is placed at a distance of 50 cm from the optical centre of this lens. State…
The power of a lens is+4D. Find the focal length of this lens. An object is placed at a distance of $\displaystyle 50$ cm from the optical centre of this lens. State the nature and magnification of the image formed by the lens and also draw a ray diagram to justify your answer.
Marking-scheme solution
Focal length of lens, \(\displaystyle \mathrm{f}(\mathrm{m})=\frac{1}{\mathrm{P}}\)
\[\mathrm{P}=+4 \cdot 0 \mathrm{D}
\]
\[\Rightarrow f=\frac{1}{+4 D}=0.25 m=25 c m
\]
Real and inverted
Magnification \(\displaystyle =-1\)
[Deduct \(\displaystyle \frac{\mathbf{1}}{\mathbf{2}}\) mark if direction of rays is not marked]All Light - Reflection and Refraction questions2023 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 2023 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.