martes, 3 de septiembre de 2019

Fundamentals of modern physics course, fall 2019




Dear classmates ...

Solve the following exercises:

1. Gold has a work function of 4.83 eV.

a) What is the value of the threshold frequency? I.e., what is the lowest frequency for electromagnetic radiation incident on a gold surface if photoelectrons are to be emitted in the photoelectric effect? Answer ___________

b) Now suppose that ultraviolet light with a wavelength of 150 nm shines on a gold surface. What is the stopping potential? I.e., what is the potential of the collector relative to the emitter which will barely prevent electrons from making it to the collector and producing a current? Answer ___________

2. if we assume the following: Our Sun has a surface temperature of about 6000 K. A particular blue giant has a surface temperature of 30,000 K. And a particular red dwarf has a surface temperature of 3000 K.

For each of these stars, determine λmax , the wavelength at the peak in the plot of intensity versus wavelength. Sun ______________ blue giant _____________ red dwarf _____________


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