NEETPhysicsCurrent Electricity
Statement (I) : The temperature coefficient of resistance for most of meals in pure form is positive. Statement (II) : A metal wire 2 ~mm in diameter carries a charge of 360 C in two hours. If the metal contains 5 10²² free electrons / cm ^3 , then drift velocity of the electrons in the wire is 6.25 10⁻⁶ ~m / s . Statement (III) : Semiconductors like pure germanium does not obey Ohm's law for all range of electric fi
Options
- AStatements I, II, III are true.
- BStatements I, II are true, but statement III is false.
- CStatements II, III are true, but statement I is false.
- DStatements I, II, III are false.
Correct answer
A. Statements I, II, III are true.
Step-by-step solution
For all metal, temperature coefficient is always positive So (I) is true We have aligned & V _ d = i neA = 360 7200 5 10²⁸ 1.6 10⁻¹⁹ (1 10⁻³ )^2 & =6.25 10⁻⁶ ~m / s aligned So, (II) is true Only metals obey ohm law therefore (III) is correct.