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प्रश्न
Give the applications photocell.
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उत्तर
Applications of photocells:
- Photocells have many applications, especially as switches and sensors.
- Automatic lights that turn on when it gets dark use photocells, as well as street lights that switch on and off according to whether it is night or day.
- Photocells are used for the reproduction of sound in motion pictures and are used as timers to measure the speeds of athletes during a race.
- Photocells are used to measure the intensity of the given light and to calculate the exact time of exposure.
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संबंधित प्रश्न
How will you define threshold frequency?
Mention the different types of photocells.
Define stopping potential.
Briefly discuss the observations of Hertz, Hallwachs and Lenard.
Explain how frequency of incident light varies with stopping potential.
Explain the quantum concept of light.
Explain experimentally observed facts of the photoelectric effect with the help of Einstein’s explanation.
Calculate the energies of the photons associated with the following radiation:
- violet light of 413 nm
- X-rays of 0.1 nm
- radio waves of 10 m
When a light of frequency 9 × 1014 Hz is incident on a metal surface, photoelectrons are emitted with a maximum speed of 8 × 105 ms−1. Determine the threshold frequency of the surface.
UV light of wavelength 1800 Å is incident on a lithium surface whose threshold wavelength is 4965 Å. Determine the maximum energy of the electron emitted.
