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?
The main function of the commutator in a simple d.c. motor is to
The falling of light energy on a metal such that electrons are liberated from the metal is called
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?
