When an astronomical telescope is in normal adjustment, the focal length of the objective lens is 50cm and that of the eye piece is 5.0cm. What is the distance between the lenses?
An object 3.00m high is placed at a distance of 7.50m from a pin-hole camera. If the image height is 6.00 cm, what is the distance of the film from the pin-hole?
A transformer is connected to a 250 V a.c. supply. The primary coil has 5000 turns and the secondary voltage is found to be 10 V. What is the number of turns in the secondary coil?
