Question

Which one is not true for magnetic field lines ?

• A. They do not intersect each other.
• B. Outside the magnet, they are from North pole to South pole.
• C. Outside the magnet, they are from South pole to North pole.
• D. They form closed loop.

Hint:

Remember the key properties of magnetic field lines: they never intersect, they originate from the North pole and terminate at the South pole outside the magnet, and they form continuous closed loops, extending from the South pole to the North pole inside the magnet.

Answer 1

The Correct Option is C

Step 1: Analyze property (1) - "They do not intersect each other."
Magnetic field lines never intersect each other. If they did, it would mean that at the point of intersection, the magnetic field would have two directions, which is impossible. So, statement (1) is true. Step 2: Analyze property (2) - "Outside the magnet, they are from North pole to South pole."
Conventionally, the direction of magnetic field lines outside a magnet is taken from the North pole to the South pole. So, statement (2) is true. Step 3: Analyze property (3) - "Outside the magnet, they are from South pole to North pole."
As established in Step 2, outside the magnet, the direction of magnetic field lines is from North pole to South pole. Therefore, the statement that they are from South pole to North pole outside the magnet is false. This statement is the one that is NOT true. Step 4: Analyze property (4) - "They form closed loop."
Magnetic field lines form continuous closed loops. They emerge from the North pole and merge at the South pole outside the magnet, and inside the magnet, their direction is from the South pole to the North pole, thus forming closed loops. So, statement (4) is true. Step 5: Identify the statement that is not true.
Based on the analysis, statement (3) is the one that is not true. $$(3) Outside the magnet, they are from South pole to North pole.$$