Physics Current Electricity MDCAT 2010
PMDC Verified Question 107 of 112
The substances like germanium and silicon have
A
Negative temperature coefficient
B
Positive temperature coefficients
C
Both A and B
D
None of the above
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Negative temperature coefficient
Concept:

Germanium and silicon are intrinsic semiconductors. Their resistance behavior differs fundamental from metals.

Solution:

  • In semiconductors, increasing temperature breaks covalent bonds, freeing more electron-hole pairs for conduction.


  • Because charge carrier density increases drastically, the overall resistance decreases as temperature rises.


  • A decrease in resistance with an increase in temperature means they possess a negative temperature coefficient (\(\alpha < 0\)).


Why other options are incorrect:

  • Opt B: Metals (conductors) have a positive temperature coefficient.


  • Opt C & D: A material cannot be both uniformly intrinsic at the same time.

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