Light - Reflection and Refraction — Class 10 Science PYQs

A convex lens of focal length $15\mathrm{cm}$, is forming a real image. If the size of image is same as the size of object, then position of object and position of image will be, respectively :

The given figure shows image formation by a lens. Analyse the figure and answer the following questions :
(a) What is the type of lens used for image formation in the given ray diagram ?
(b) If the real image is formed at a distance of $30\mathrm{cm}$ from the lens and the size of image is twice the size of the object, then where was the object placed ?

Read the following passage and answer the questions given :

Mirror 'X' is used to concentrate sunlight in solar furnace and Mirror 'Y' is fitted on the side of the vehicle to see the traffic behind the driver. Which of the following statements are true for the two mirrors ?
(i) The image formed by mirror 'X' is real, diminished and at its focus.
(ii) The image formed by mirror 'Y' is virtual, diminished and erect.
(iii) The image formed by mirror 'X' is virtual, diminished and erect.
(iv) The image formed by mirror 'Y' is real, diminished and at its focus.

An object is placed at a distance of $60\mathrm{cm}$ from a concave lens of focal length $30\mathrm{cm}$. Use lens formula to find the position of the image formed in this case.

Draw ray diagrams to show the nature, position and relative size of the image formed by a convex mirror when the object is placed (i) at infinity and (ii) between infinity and pole P of the mirror.

(a) (i) The power of a lens 'X' is $-2.5\mathrm{D}$. Name the lens and determine its focal length in cm. For which eye defect of vision will an optician prescribe this type of lens as a corrective lens ?
(ii) "The value of magnification '$m$' for a lens is $-2$." Using new Cartesian Sign Convention and considering that an object is placed at a distance of $20\mathrm{cm}$ from the optical centre of this lens, state :
(I) the nature of the image formed;
(II) size of the image compared to the size of the object;
(III) position of the image, and
(IV) sign of the height of the image.
(iii) The numerical values of the focal lengths of two lenses A and B are $10\mathrm{cm}$ and $20\mathrm{cm}$ respectively. Which one of the two will show higher degree of convergence/divergence ? Give reason to justify your answer.
OR
(b) (i) Draw a ray diagram to show the refraction of a ray of light through a rectangular glass slab when it falls obliquely from air into glass.
(ii) State Snell's law of refraction of light.
(iii) Differentiate between the virtual images formed by a convex lens and a concave lens on the basis of :
(I) object distance, and
(II) magnification.

An object is placed at a distance of $30\mathrm{cm}$ in front of a concave mirror of focal length $20\mathrm{cm}$. Use mirror formula to determine the position of the image formed in this case.

An object is placed at a distance of $10\mathrm{cm}$ in front of a concave mirror of focal length $15\mathrm{cm}$. Use mirror formula to determine the position of the image formed by this mirror.

If the absolute refractive indices of two media X and Y are $\frac{6}{5}$ and $\frac{4}{3}$ respectively, then the refractive index of Y with respect to X will be :