CBSE 2025 · Region 3 · Set 1 · Q36 · 5 marks
(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 with the help of a ray diagram. What happens when a ray of light falls normally on one of the faces of a rectangular glass prism ? Draw diagram.(ii)An object is placed at a distance of $\displaystyle 30$ cm from the optical centre of a concave lens of focal length $\displaystyle 20$ cm. Use Lens formula to determine the position of the image formed in this case.(i)A student wishes to study the image formation by a concave mirror using candle flame as object. State the type of the image formed by the mirror and mention the change in the image formed, if any, that he observes when the candle flame is gradually moved away from the pole of the mirror. Draw a ray diagram to show the image formation when the object distance is nearly equal to the radius of curvature of the mirror.(ii)A convex mirror used for rear-view on an automobile has a focal length of $\displaystyle 3$‧$\displaystyle 0$ m. If a bus is located at $\displaystyle 6.0$ m from this mirror, use mirror formula to find the position of the image of the bus as seen in the mirror.
(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 with the help of a ray diagram. What happens when a ray of light falls normally on one of the faces of a rectangular glass prism ? Draw diagram.
(ii)
An object is placed at a distance of $\displaystyle 30$ cm from the optical centre of a concave lens of focal length $\displaystyle 20$ cm. Use Lens formula to determine the position of the image formed in this case.
(i)
A student wishes to study the image formation by a concave mirror using candle flame as object. State the type of the image formed by the mirror and mention the change in the image formed, if any, that he observes when the candle flame is gradually moved away from the pole of the mirror. Draw a ray diagram to show the image formation when the object distance is nearly equal to the radius of curvature of the mirror.
(ii)
A convex mirror used for rear-view on an automobile has a focal length of $\displaystyle 3$‧$\displaystyle 0$ m. If a bus is located at $\displaystyle 6.0$ m from this mirror, use mirror formula to find the position of the image of the bus as seen in the mirror.
Marking-scheme solution
(i)
The extent of bending of the ray of light at the opposite parallel faces of the rectangular glass slab is equal and opposite. This is why the ray emerges parallel to the incident ray.
\[\begin{aligned}
\frac{1}{\mathrm{v}}= & \frac{1}{+3 \cdot 00 \mathrm{~m}}-\frac{1}{(-6 \cdot 00 \mathrm{~m})} \\
=\frac{1}{+3 \cdot 00 \mathrm{~m}}+\frac{1}{6 \cdot 00 \mathrm{~m}} & =\frac{2+1}{6 \mathrm{~m}} \\
\text { or } \mathrm{v} & =\frac{6}{3}=2 \cdot 0 \mathrm{~m}
\end{aligned}
\]
Light - Reflection and RefractionRefraction of Light and Refractive IndexApplylong_answerhard
More from Light - Reflection and Refraction
- 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×
- Identify from the following the ray diagram which shows the correct path of the reflected ray for the ray…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.