Question

Two parallel conductors carrying current in the same direction attract each other, while two parallel beams of electrons moving in the same direction repel each other. Which of the following statement provide part of all of the reason for this ? (Choose the incorrect option)
A. The conductors are electrically netural
B. The conductors produce magnetic fields on each other
C. The electrons beams do not produce magnetic field on each other
D. The magnetic forces caused by the electron beams on each other are weaker than the electrostatic forces between them

Answer 1

Correct Answer - C

`F_(m) = (mu_(0))/(4pi)(e.e.v.v)/(r^(2)) = (mu_(0)e^(2)v^(2))/(4pi r^(2))`
`F_(e) = (1)/(4pi in_(0)).(e.e)/(r^(2))`
`(F_(e))/(F_(m)) = (1)/(mu_(0) in_(0)v^(2)) = (c^(2))/(v^(2))`
Since `c gt gt v, F_(e) gt gt F_(m)`

`F_(m) = (mu_(0)i.i)/(2pi d) = (mu_(0)i^(2))/(2 pi d)`