Question

Which statement correctly describes Gauss law for magnetism
• The net Magnetic flux through any closed surface is Zero
• Magnetic field lines always form closed loops
• Isolated magnetic monopole exists.
• The source of magnetic field are electric currents or changing electric fields. Choose the correct answer from the options given below:

• A. A & B Only
• B. A, B & D Only
• C. B, C & D Only
• D. A, B & C Only

Hint:

Gauss law for magnetism: \[ \oint \vec B\cdot d\vec A =0 \] This means magnetic monopoles do not exist and magnetic field lines always form closed loops.

Answer 1

The Correct Option is B

Concept: Gauss's law for magnetism is one of Maxwell's equations and explains the nature of magnetic field lines. The law states that: \[ \boxed{ \text{Net magnetic flux through a closed surface is zero} } \] This implies:
• Magnetic monopoles do not exist independently.
• Magnetic field lines always form closed loops.

Step 1: Write Gauss's law for magnetism mathematically. Gauss law for magnetism is expressed as: :contentReference[oaicite:0]{index=0} This means:
• Total magnetic flux entering a closed surface equals total magnetic flux leaving it. Hence net magnetic flux is zero. Therefore Statement A is correct.

Step 2: Understand magnetic field lines. Because isolated north or south magnetic poles do not exist:
• Magnetic field lines cannot start or end independently.
• They always form continuous closed loops. Thus: \[ \boxed{ \text{Magnetic field lines form closed loops} } \] Hence Statement B is correct.

Step 3: Analyze statement about magnetic monopoles. Statement C says: “Isolated magnetic monopole exists” Experimentally:
• No isolated magnetic monopole has been observed. Whenever a magnet is broken:
• Both north and south poles appear again. Therefore Statement C is incorrect.

Step 4: Analyze source of magnetic field. Magnetic fields are produced by:
• Electric currents
• Time varying electric fields This follows from Ampere-Maxwell law. Hence Statement D is also correct.

Step 5: Determine correct combination. Correct statements are: \[ A,\ B,\ D \] Incorrect statement: \[ C \] Thus: \[ \boxed{ A,\ B\ \&\ D\ \text{Only} } \]

Step 6: Choose the correct answer. Hence the correct option is: \[ \boxed{(2)} \] Final Conclusion: Gauss law for magnetism implies:
• Net magnetic flux through closed surface is zero.
• Magnetic field lines form closed loops.
• Magnetic monopoles do not exist. Hence, the correct answer is: \[ \boxed{(2)} \]