Question

A circular loop of wire has current going through it in the clockwise direction. What is the direction of the magnetic field that is caused by this current through the wire?
$\begin{align}
  & \text{A}\text{. Inside the loop: out of the screen} \\
 & \text{ Outside the loop: into the screen} \\
\end{align}$
$\begin{align}
  & \text{B}\text{. Inside the loop: out of the screen} \\
 & \text{ Outside the loop: out of the screen} \\
\end{align}$
$\begin{align}
  & \text{C}\text{. Inside the loop: into the screen} \\
 & \text{ Outside the loop: out of the screen} \\
\end{align}$
$\begin{align}
  & \text{D}\text{. Inside the loop: into the screen} \\
 & \text{ Outside the loop: into the screen} \\
\end{align}$

Answer 1

Hint: Maxwell’s right hand thumb rule can be used to determine the direction of magnetic field that is caused by the current in the circular loop of the wire. According to Maxwell’s right hand thumb rule, when we point our right hand thumb in the direction of current flowing in a straight conductor then the curled finger of the same hand provides us the direction of the magnetic field due to that electric current.

Complete step-by-step answer:
According to Maxwell’s right hand thumb rule, “when we point our right hand thumb in the direction of current in wire, then the curled fingers of the same hand show the direction of the magnetic field.”
In case of circular loop, it states that, “if we curl our fingers of right hand in direction of current, the thumb of same hand gives us direction of magnetic field inside the loop.”
As current is flowing clockwise, when we curl our fingers of right hand clockwise, our right hand thumbs point inwards. Therefore we conclude that inside the loop direction of the magnetic field is into the screen.

Magnetic field lines have a property that they form closed loops which do not end. As magnetic field lines point in the direction of the magnetic field, inside the loop field lines will point inward. Therefore, out of the loop, magnetic field lines will point out of the screen.
This shows us that the magnetic field outside the loop is out of the screen.
So, the correct answer is “Option C”.

Note: Magnetic field is produced by moving charge just the same as the electric field is produced by a static charge. Any charge moving in a magnetic field experiences force in direction perpendicular to its own direction and direction of magnetic field.