Task id17072

To determine the magnetic field induction in the gap between the poles of an electromagnet, a frame with an area of 3.2 cm2 was placed in it, containing 50 turns of thin wire and connected to a ballistic galvanometer with a resistance of 100 Ohms and a constant of 2·10-5 C/div. When the frame was pulled out of the field, the galvanometer needle deviated by 20 divisions. What is the field induction?