Find the distance of the image from object O, formed by the combination of lenses in the figure :

Car B overtakes another car A at a relative speed of 40 ms^$$-$$1. How fast will the image of car B appear to move in the mirror of focal length 10 cm fitted in car A, when the car B is 1.9 m away from the car A?

The expected graphical representation of the variation of angle of deviation '$$\delta$$' with angle of incidence 'i' in a prism is :

The relative permittivity of distilled water is 81. The velocity of light in it will be :

(Given $$\mu$$_r = 1)