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A small metal plate (work function W) is kept at a distance d from a singly ionized, fixed ion. A monochromatic light beam is incident on the metal plate and photoelectrons re emitted. Find the maximum wavelength of the light beam so that some of the photoelectrons may go round the ion along a circle. |
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Answer» SOLUTION :Electron is moving around the ion in a Circle of radius .d.. Centripetal force is PROVIDED by Electrostatic force `(1)/(4piepsi_(0))(e^(2))/(d^(2))=(mV^(2))/(d),:.mV^(2)=(1)/(4piepsi_(0))(e^(2))/(d)` `:.K.E=(1)/(8piepsi_(0))(e^(2))/(d)"".......(1)` But `K.E_(max)=(hc)/(LAMDA)-W""......(2)` `:.(hc)/(lamda)-W=(e^(2))/(8piepsi_(0)d)` `:.lamda=(hc8piepsi_(0)d)/(e^(2)+8piepsi_(0)dW)` 
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