Answer to Question #61335 in Electricity and Magnetism for muhammad umar

Question

19) Kirchhof's loop rule is statement of conservation of -----------
a)mass
b) energy
c) charge
d) momentum
20)In the space surrounding a wire carrying a steady current, there exists
a) a magnetic field pointing radially outward
b) a magnetic field circling the wire
c) an oscillating magnatic field
d) no magnatic field

Answer 1

b) energy
The Kirchhoff’s loop rule states that the sum of the voltage drops around any closed circuit is zero. In other words, if we choose the starting point in the closed loop and will go around that loop, when we arrive back at the starting point it has the same potential as it did when we began. By the definition, voltage (or potential difference) is the difference in electric potential energy between two points per unit electric charge. Also, as we know, the law of conservation of energy states that the energy is neither created nor destroyed. Therefore, Kirchhoff's loop rule is statement of conservation of energy.

b) a magnetic field circling the wire
The magnetic field lines around the long wire which carries an electric current form concentric circles around the wire. Therefore, the correct answer is b) a magnetic field circling the wire.