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.
Promotional Banner

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.

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.

CHHAYA PUBLICATION-SEMICONDUCTORS AND ELECTRONICS -HIGHER ORDER THINKING SKILL (HOTS) QUESTIONS
  1. When a semiconductor is irradiated by light of definite wavelength its...

    Text Solution

    |

  2. What happens if the amount of reverse bias in a p-n junction diode is ...

    Text Solution

    |

  3. At absolute zero temperature the conductivities of both the insulators...

    Text Solution

    |

  4. You are given two bars of same resistance, one of them is a conductor ...

    Text Solution

    |

  5. Draw the voltage-current charateristics of a p-n junction and compare ...

    Text Solution

    |

  6. What is the effect of doping on the depletion layer of a p-n junction?

    Text Solution

    |

  7. Why does the conductivity of a pure semiconductor increases with rise ...

    Text Solution

    |

  8. In which kind of biasing of a p-n junction the net holes flows the n-r...

    Text Solution

    |

  9. Explain why the resistance of a semiconductor decreases with increase ...

    Text Solution

    |

  10. In a transistor the base is made very thin. ExpIain the reason.

    Text Solution

    |

  11. Why is a transistor caIIed temperature- sensitive device?

    Text Solution

    |

  12. In a transistor the forward bias is aIways smaII as compared to the re...

    Text Solution

    |

  13. ExpIain why the input resistance of a transistor is Iow whiIe the outp...

    Text Solution

    |

  14. The gain of a common- emitter ampIifier is given by A(v)=-g(m)R(L) . D...

    Text Solution

    |

  15. If the emitter and base of a transistor have same doping concentration...

    Text Solution

    |

  16. How wiII you test wheather a transistor is damaged or not?

    Text Solution

    |

  17. Under normaI use of transistors, the emitter is forwerd biased whiIe t...

    Text Solution

    |

  18. Can two separate p-n junction diodes placed back to back be used to fo...

    Text Solution

    |