Q3) Two biconvex lenses have f₁ = +15 cm and f2 = +25 cm respectively. i) If the two lenses are placed in effective contact, what is the focal length of the compound lens? ii) If the two lenses are placed coaxially with a separation of d what are the front focal length and the back focal length ? = = 10 cm, with lens 1 to the left, 40 cm, and a laser beam of di- iii) If the two lenses are placed coaxially with a separation d ameter 2 mm is incident parallel to the axis onto lens 1, what is the diameter of the output beam ?

Q3) Two biconvex lenses have f₁ = +15 cm and f2 = +25 cm respectively. i) If the two lenses are placed in effective contact, what is the focal length of the compound lens? ii) If the two lenses are placed coaxially with a separation of d what are the front focal length and the back focal length ? = = 10 cm, with lens 1 to the left, 40 cm, and a laser beam of di- iii) If the two lenses are placed coaxially with a separation d ameter 2 mm is incident parallel to the axis onto lens 1, what is the diameter of the output beam ?