Question 15: NCERT Solutions for 12th Class Physics: Chapter 9-Ray Optics and Optical Instruments
Use the mirror equation to deduce that:
(a) An object placed between f and 2f of a concave mirror produces a real image beyond 2 f.
(b) A convex mirror always produces a virtual image independent of the location of the object.
(c) The virtual image produced by a convex mirror is always diminished in size and is located Between the focus and the pole.
(d) An object placed between the pole and focus of a concave mirror produces a virtual and enlarged image.
Solution:
(a) We know for a concave mirror ƒ < 0 [negative] and u < 0 [negative]
(b) For a convex mirror, ƒ > 0, always positive and object distance u < 0, always negative.
So, whatever be the value of u, a convex mirror always forms a virtual image.
(c) In convex mirror focal length is positive hence ƒ > 0 and for an object distance from mirror with negative sign (u < 0)
hence the image is located between pole and focus of the mirror
So, the image is virtual and diminished.
(d) In concave mirror, ƒ < 0 for object placed between focus and pole of concave mirror
Check the complete chapter with solutions.
NCERT Solutions for 12th Class Physics: Chapter 9-Ray Optics and Optical Instruments