Answer:
Diameter will be 351.42 mm
Explanation:
We have given current flowing in the copper wire i = 310 A
Voltage drop across the wire V = 0.55 volt
We know that resistance is given by 
Length of the copper wire l = 1 m
Resisitivity of the copper wire 
We know that resistance 


As area 


So diameter
= 351.42 mm
Answer:
Cuba, Jamaica, Dominican Republic, Haiti, Turks & Caicos, and The Bahamas
Explanation:
Electromagnets have certain advantages over permanent magnets. One of the major advantage is, the amount of electric current can easily be controlled, in turn, magnetic field can be controlled. Out of all the options, option D would be the best answer.
In short, Your Answer would be option D) Electromagnets can easily be turned on and off.
Hope this helps!
Answer:
Option d is correct.
Explanation:
We know , resistance of a body is directly proportional to its length and inversely proportional to its area.
( Here,
is constant dependent on object material )
Writing
also :
( since they are of same material therefore,
is same.)
Now , if
.
Then 
Therefore, option d. is correct.
Hence, this is the required solution.