Question

(a) (i) State the laws of refraction of light. (ii) Write a relation between the angle of incidence (i), angle of emergence (e), angle of prism (A) and angle of deviation (d) for a ray of light passing through an equilateral prism. 

(b) An object is placed in front of a lens between its optical centre and the focus and forms an erect, virtual, and diminished image. 

(i) Name the lens which formed this image. 

(ii) Draw a ray diagram to shows the formation of the image.

Answer 1

(a) 

(i) Laws of Refraction : 

(a) The incident ray, the refracted ray and the normal at the point of incidence, all lie in the same plane. 

(b) The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant for the pair of given media. 

(ii) ∠i + ∠e = A + d 

(b) 

(i) Lens is concave. 

(ii) AD is object between focus and optical centre A’D’ is image. The ray diagram is shown.