For insulators and semiconductors, the resistance decreases with an increase in temperature because:
Number density of charge carriers increases
In semiconductors and insulators, resistance decreases with increasing temperature because:
- Unlike conductors, where increased temperature increases electron scattering, in semiconductors, heat excites more charge carriers (electrons and holes).
- More charge carriers reduce resistance as more free electrons are available to conduct electricity.
Thus, the correct answer is (b) Number density of charge carriers increases.
Important Questions from Ray Optics and Optical Instruments
A Convex mirror produces the magnification 1/3 and 1/4 when the object is placed at the points P and Q in front of the mirror.
Which of the following statements are correct?
- A. The saturation current is constant with collector plate potential for different frequencies of incident radiation.
- B. The saturation current is different with collector plate potential for different frequencies of incident radiation.
- C. The saturation current is different with collector plate potential for different intensity of incident radiation.
- D. The saturation current is constant with collector plate potential for different intensity of incident radiation.
- E. Below threshold frequency, no photoelectrons are emitted.
Choose the correct answer from the options given below:
A ray of light passes through four transparent media with refractive index μ1, μ2, μ3, and μ4 as shown in the figure. The surfaces of all media are parallel. If BC and DE are parallel, we must have:
Light of uniform intensity shines perpendicularly on a totally absorbing surface, fully illuminating the surface. If the area of the surface is decreased, what is the effect on radiation pressure?
A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence, and each of these angles is equal to (3/4)th of the angle of the prism. The angle of deviation is:
