Question

Assertion A: Superconductivity arises from electrons forming Cooper pairs due to electron phonon interaction Reason R: Cooper pairs have lower energy and move without scattering leading to zero resistance In the light of the above statements, choose the most appropriate answer from the options given below
• Both A and R are correct and R is the correct explanation of A
• Both A and R are correct but R is NOT the correct explanation of A
• A is correct but R is not correct
• A is not correct but R is correct

• A. Both A and R are correct and R is the correct explanation of A
• B. Both A and R are correct but R is NOT the correct explanation of A
• C. A is correct but R is not correct
• D. A is not correct but R is correct

Hint:

In superconductors:
• Electrons form Cooper pairs
• Cooper pairs move without scattering
• Resistance becomes zero

Answer 1

The Correct Option is A

Concept: Superconductivity is a quantum phenomenon in which electrical resistance becomes exactly zero below a critical temperature. BCS theory explains superconductivity using: \[ \boxed{ \text{Cooper pair formation} } \]

Step 1: Analyze Assertion A. Assertion says: “Superconductivity arises from electrons forming Cooper pairs due to electron-phonon interaction.” This is correct. According to BCS theory:
• Lattice vibrations (phonons) mediate attraction between electrons.
• Electrons form bound pairs called Cooper pairs. Hence Assertion A is true.

Step 2: Analyze Reason R. Reason says: “Cooper pairs have lower energy and move without scattering leading to zero resistance.” This is also correct. Because Cooper pairs:
• Occupy coherent quantum state
• Move collectively
• Avoid scattering from lattice defects Therefore electrical resistance becomes zero. Hence Reason R is true.

Step 3: Check whether R explains A. Reason explains:
• Why Cooper pairing causes superconductivity.
• Why resistance vanishes. Thus Reason correctly explains Assertion. Hence: \[ \boxed{ \text{Both A and R are true and R explains A} } \]

Step 4: Choose the correct answer. Therefore the correct option is: \[ \boxed{(1)} \] Final Conclusion: Both Assertion and Reason are correct and Reason correctly explains Assertion. Hence, the correct answer is: \[ \boxed{(1)} \]