Q1. The radius of curvature of a spherical mirror is 30 cm. What is its focal length ? Q2. An object is placed at (a) 10 cm, (b) 5 cm in front of a concave mirror of radius of curvature 15 cm. Find the position, nature, and magnification of the image in each case. Q3. What do you understand by term ‘reflection of light’ ? Q4. Define refractive index of a medium. Q5. Define optical centre of a lens. Q6. Define the first principle focus of a convex lens. Q7. Define the focal length of a lens. Q8. What do you understand by the term ‘power of lens’ ? Q9. Give two characteristics of the image formed by a concave lens . Q10. State two application of convex lens . Q11. What is the unit of refractive index ? Q12. What is the refractive index of vacuum ? Q13. Which of the two is a diverging lens : convex or concave ? Q14. A lens forms an inverted image of an object. What kind of lens is this ? Q15. Give the name of the point on the principle axis of a lens through which light passes undeviate
