Law of Biot-Savart

Question 1

What is the law of Biot-Savart?

Answer 1

B(r,t)=μ0qv(t)x(r-r’(t))/4πabs((r-r’(t)^3))

Question 2

What is this law valid for?

Answer 2

For constant velocities

Question 3

What is then ratio of the magnetic to electric force?

Answer 3

abs(F_B)/abs(F_E)=(v/c)^2

Question 4

What is Biot-Savart for a wire?

Answer 4

B(r)=μ0/4π ∫I dr’x(r-r’)/abs((r-r’)^3)

Question 5

What is the magnetic field of a straight wire?

Answer 5

B(r)=μ0I/2πR φ(hat)

Question 6

For two current loops when do they attract each other?

Answer 6

When the currents are in the same direction

Question 7

For two current loops when do they repel each other?

Answer 7

When the currents are in the opposite direction