an object 50 cm tall is place on the principle axis of a convex lens. its 20cm tall image is formed on the screen placed at a distance of 10cm from the lens. find the focal length of the lens

Apiano tuner uses a tuner to create a tone of 5.00 x 10² hz. when a key on the piano is struck he hears 5 beats per second. what is a possible frequency of vibration for the piano string? 2500 hz 1300 hz 605 hz 495 hz

Suppose a comet has an orbital period of 309.1 years around the sun. what is it’s average distance from the sun?

The electric field direction is defined by the direction of the force felt by (select one of the following answers): 1. a negative charge. 2. a positive charge. 3. both positive and negative charges.