Concepts Of Physics MCQ Edition [Volume 2]
- Exam
- Concepts Of Physics MCQ Edition [Volume 2]
- Subject
- Physics
- Chapter
- Thermal and Chemical Effects of Electric Current
Concepts Of Physics MCQ Edition [Volume 2] · Physics · Thermal and Chemical Effects of Electric Current
Consider the two statements given below. (A) The free-electron...
Consider the two statements given below.
(A) The free-electron density varies among different metals.
(B) The free-electron density in a metal is dependent on temperature.
The Seebeck effect occurs
(A) The free-electron density varies among different metals.
(B) The free-electron density in a metal is dependent on temperature.
The Seebeck effect occurs
Options
- Abecause of neither A nor B
- Bbecause of both A and B
- Cbecause of B but not A
- Dbecause of A but not B
Correct answer
B. because of both A and B
Step-by-step solution
The Seebeck effect is the phenomenon of generation of an electromotive force (EMF) in a circuit containing two dissimilar metals whose junctions are maintained at different temperatures.
The free-electron density varies from metal to metal. When two different metals are joined, electrons diffuse from the metal with higher free-electron density to the one with lower free-electron density, creating a contact potential difference at the junction.
Furthermore, the free-electron density and the kinetic energy of free electrons in a metal depend on temperature. This causes the contact potential difference at the hot junction to be different from that at the cold junction, resulting in a net EMF in the closed loop.
Thus, the Seebeck effect occurs because of both the variation of free-electron density among different metals and its dependence on temperature.
The free-electron density varies from metal to metal. When two different metals are joined, electrons diffuse from the metal with higher free-electron density to the one with lower free-electron density, creating a contact potential difference at the junction.
Furthermore, the free-electron density and the kinetic energy of free electrons in a metal depend on temperature. This causes the contact potential difference at the hot junction to be different from that at the cold junction, resulting in a net EMF in the closed loop.
Thus, the Seebeck effect occurs because of both the variation of free-electron density among different metals and its dependence on temperature.