Question

1.) Motors and generators  

a) In a homopolar motor (like Faraday’s motor), what happens to the motion if the current is reversed?

b) Who was William Sturgeon and what was his connection to motor improvement?

c) What is the voltage induced in a generator with 974 turns, an area of 195 mm² turning at a rate of 42 rpm with a constant field of 0.0209 T?

Answer 1

(a)In a homopolar motor (like Faraday’s motor), what happens to the motion if the current is reversed then the direction of the rotation of the blades will be also reversed.

(b) William Sturgeon was an English electrical engineer. In 1825 he built the first practical electromagnet, in 1832 invented the commutator for electric motors and in 1836 made the first moving-coil galvanometer and carried out research into atmospheric charge. His Annals of Electricity (1836) was the first journal of its kind in Britain. His electromagnet was capable of supporting more than its own weight. This device led to the invention of the telegraph, the electric motor, and numerous other devices basic to modern technology.

(c) Since, induced emf = NBA

Here, N= 974, B = 0.0209 T, A = 195 mm² = 195 x 10^-6 m² and  =42 rpm = 4.398 rad/s

Therefore, induced emf = (974)(0.0209 T)(195 x 10^-6 m²)(4.398 rad/s) = 0.01746 Volts