Electro Magnetic Induction And Alternating Currents Question 337

Question: is a circular loop of radius r and resistance R. A variable magnetic field of induction B=B0et is established inside the coil. If the key (K) is closed, the electrical power developed right after closing the switch is equal to

Options:

A) B02πr2R

B) B010r3R

C) B02π2r4R5

D) B02π2r4R

Show Answer

Answer:

Correct Answer: D

Solution:

P=e2R;  e=ddt(BA)=Addt(Boet)=ABoet
P=1R(ABoet)2=A2Bo2e2tR At the time of starting t = 0 so P=A2Bo2R
P=(πr2)2Bo2R=Bo2π2r4R



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