Discussion
The correct statement for shot noise and Johnson noise is that :
(a) Shot noise occurs because the carriers do not cross the barrier simultaneously
(b) Shot noise is a random fluctuation that accompanies any direct current crossing a potential barrier
(c) Johnson noise arises from thermal cause wherein electron in conductor possess kinetic energy
(d) Mean noise voltage across the conductor is zero but the root-mean-square value is infinite and cannot be measured
Answer: B
Statements a, b and c are correct, so the answer is (a), (b) and (c).
Shot noise arises because current is carried by discrete charges that cross a potential barrier at random times rather than simultaneously (a); it is a random fluctuation that accompanies any direct current crossing a barrier, as in diodes and transistors (b). Johnson (thermal) noise arises from the random thermal motion of electrons, which have kinetic energy, in any conductor (c).
Statement d is false. The mean of thermal noise voltage is zero, but its root-mean-square value is finite and measurable:
\[ V_{rms} = \sqrt{4kTRB} \]
so the option 'd only' and any option omitting b or c are wrong.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development