Home
Class 12
PHYSICS
When a semiconductor is irradiated by li...

When a semiconductor is irradiated by light of definite wavelength its resistance decreases.Exaplain why.

Text Solution

Verified by Experts

In a semiconductor greater the number of electron hole pair produced greater will be its electrical conductivity and of definite wavelength is fixed. If the energy of photons of light of definite wavelength is fixed. If the energy of photon incident on a semiconductor be equal to the difference in the energy level between conduction band and valence band an electron transits from valence band to conduction band by generating a hole in the valence band. Due to increases in electrical conductivity of a semiconductor its resistance decreases.
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • SEMICONDUCTORS AND ELECTRONICS

    CHHAYA PUBLICATION|Exercise NCERT TEXTBOOK QUESTIONS WITH ANSWER HINT|9 Videos

  • SEMICONDUCTORS AND ELECTRONICS

    CHHAYA PUBLICATION|Exercise NCERT EXEMPLAR QUESTIONS WITH ANSWER HINT (Single Option Correct )|6 Videos

  • SEMICONDUCTORS AND ELECTRONICS

    CHHAYA PUBLICATION|Exercise Section Related Questions|55 Videos

  • REFRACTION OF LIGHT

    CHHAYA PUBLICATION|Exercise CBSE SCANNER|11 Videos

Similar Questions

Explore conceptually related problems

The angular width of central maximum of a Fraunhofer diffraction fringe formed by a narrow slit is measured. For this, the slit is illuminated by a light of wavelength 6000 Å. When the slit is illuminated by light of another wavelength, it is found that the angular width decreases by 30%. Find the wavelength of the light used in the second case. Now, in the first case, the total set-up of the experiment is immersed in a liquid. It is found that, the angular width of central maximum decreases by same amount. Calculate the refractive index of the liquid.

When urea is added to water the freezing point decreases. Explain why.

Knowledge Check

  • When the length and area of cross-section of a wire are doubled, then its resistance

    A
    will becomes half
    B
    will be doubled
    C
    will remain the same
    D
    will become four times

    • Similar Questions

    Explore conceptually related problems

    Following results are observed when sodium metal is irradiated with different wavelengths. Calculate threshold wavelength.

    When a semiconductor device is connected in series with a battery and a resistance a current is found to flow in the circuit. If however the polarity of the battery is reversed practically no current flows in the circuit. The device may be

    What should be the change of angular width of central maximum in a single slit diffraction pattern when visible light of lower wavelength is used. Give explanation for each case.

    When a certain metal was irradiated with a light of 8.1xx10^16 Hz frequency the photoelectron emitted had 1.5 times the kinetic energy as did the photoelectrons emitted when the same metal was irradiated with light 5.8xx10^16 Hz frequency if the same metal is irradiated with light 3.846 nm wavelength what will be the kinetic energy of the photoelectron emitted?

    A reduction in O_(2) evolution occurs when light wavelength is

    Show that , if the range of an ammeter is increases n times, its resistance decreases n times.

    Kinetic energy of an electron decreases with the increases of distance of its orbit from the nucleus. But the total energy increases. Explain why.

    Home
    Profile