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### Midterm Question

Posted: Thu Dec 07, 2017 5:30 pm
Can someone please explain how to solve this question??

Dr. Discovery has recently found an Alien civilization. It seems that the aliens are using an experimental setup similar to the photoelectric experiment (effect) to provide energy for their everyday life. Fortunately, in class we discussed the photoelectric experiment in detail.
A. Their primary energy source is high-energy photons from outer space. Each photon
has an energy of 4.00 x 102 eV and the photons hit a metal surface with a work function of W = 2.90 eV, what is the speed of the emitted electrons?

### Re: Midterm Question

Posted: Thu Dec 07, 2017 6:40 pm
Use the formula Ephoton = work function + Kinetic energy of electron.
The KE of an electron is (1/2)mv^2 so Ephoton = work function + (1/2)mv^2.
Convert the 2 given energies to joules and plug them in for Ephoton and work function.
The mass of an electron is a constant so you have all the needed quantities except for v, the velocity of an electron, which you will need to solve for.