Answer:
Why are they used:
A carbon brush is a sliding contact used to transmit electrical current from a static to a rotating part in a motor or generator, and, as regards DC machines, ensuring a spark-free commutation.
Answer:constant cause it keeps happening Or it might be decreasing but I’m not sure
Answer: b or c
Explanation: on khan academy
Refrigerator was what is commonly used today. We do dry foods and salt cure but that is not done on a daily basis
