AIIMS 201827 May
- Exam
- AIIMS
- Year
- 2018
- Date
- 27 May
- Subject
- Physics
- Chapter
- Current Electricity
AIIMS 2018 · 27 May · Physics · Current Electricity
Assertion : A current flows in a conductor only when there is an...
Assertion : A current flows in a conductor only when there is an electric field within the conductor.
Reason : The drift velocity of electron in presence of electric field decreases.
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion.
- BIf both assertion and reason are true but reason is not the correct explanation of assertion.
- CIf assertion is true but reason is false.
- DIf both assertion and reason are false.
Correct answer
C. If assertion is true but reason is false.
Step-by-step solution
In the absence of external electric field, the free electrons move randomly in the conductor, so their drift velocity is zero and therefore there is no current in the conductor. In the presence of electric field, each electron in the conductor experiences a force in a direction opposite to the electric field. Now the free electrons are drifted from negative end to the positive end of the conductor and hence a current starts to flow in the conductor.