21. Assertion (A): Large concave mirrors are used to concentrate sunlight to produce heat in solar cookers. Reason (R): Concave mirror converges the light rays falling on it to a point. 22. a) Both A and R are true and R is the correct explanation of A. c) A is true but R is false. b) Both A and R are true but R is not the correct explanation of A. d) A is false but R is true. Assertion(A): Concave mirrors are used as make-up mirrors. Reason (R): When the face is held within the focus of a concave mirror, then a diminished image of the face is seen in the concave mirror. 23. a) Both A and R are true and R is the correct b) Both A and R are true but R is not the explanation of the assertion. correct explanation of A. c) A is true but R is false. d) A is false but R is true. Assertion (A): The height of an object is always considered positive. Reason (R): An object is always placed above the principal axis in the upward direction. a) Both A and R are true and R is the correct b) Both A and R are true but R is not the 24. 25. explanation of the assertion. c) A is true but R is false. correct explanation of A. d) A is false but R is true. Assertion (A): The image formed by a concave mirror is certainly real if the object is virtual. Reason (R): The image formed by a concave mirror is certainly virtual if the object is real. a) Both A and R are true and R is the correct explanation of A. c) A is true but R is false. b) Both A and R are true but R is not the correct explanation of A. d) A is false but R is true. Assertion (A): If a spherical mirror is dipped in water, its focal length remains unchanged. Reason (R): A laser light is focused by a converging lens. There will be a significant chromatic aberration. a) Both A and R are true and R is the correct explanation of A. c) A is true but R is false. b) Both A and R are true but R is not the correct explanation of A. d) A is false but R is true.