1. A photocathode has a work function of 2.9 eV. It is illuminated with white li

Question

1. A photocathode has a work function of 2.9 eV. It is illuminated with white light that has a continuous wavelength band from 400 nm to 700 nm. What is the wavelength band, in nm, in which photoelectrons are produced? Let 1 eV = 1.60 × 1019 J, the mass of an electron m = 9.11 × 1031 kg, the speed of light c = 3.00 × 108 m/s, and Planck’s constant h = 4.136 × 1015 eV s.

430 to 700

480 to 700

430 to 480

400 to 480

400 to 430

3. Monochromatic light is incident on a metal surface and electrons are ejected. Then the intensity of the light is increased while the frequency is kept constant. What changes, if any, will occur to the ejection rate and maximum energy of the electrons?

same rate; same maximum energy

greater rate; same maximum energy

greater rate; greater maximum energy

same rate; greater maximum energy

430 to 700

480 to 700

430 to 480

400 to 480

400 to 430

Explanation / Answer

a. answer is option no. 3, because n this band both sides of the wavelength will decrease.

b. if you increases the intensity of the light then the no. of electrons will eject with greater rate but energy will be the same untill you increases the frequency of the light. so option 2 is correct

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