In these diagram, the angle of refraction r is correctly marked in which diagram?

(a) Draw a ray diagram to show the formation of image of an object placed between infinity and optical center of a concave lens.

(b) A concave lens of focal length 15 cm forms an image 10 cm from the lens. Calculate

(i) the distance of the object from the lens

(ii) the magnification for the image formed

(iii) the nature of the image formed -

Different paths of ray are shown in the following figures. Which of the following is correct:

To find the focal length of a concave mirror, Sita should choose which one of the following set-ups?

Iron nails were dipped in an aqueous solution of copper soleplate. After about 30 minutes, it was observed that the color of the solution changed from