We wish to use the photoelectric effect to convert light to electrical power. A

Question

We wish to use the photoelectric effect to convert light to electrical power. A photoelectric effect test cell similar to the one shown on the right is constructed with A1 metal (work function of =4.0eV) for the photoelectric cathode. Monochromatic light of wavelength 248nm and an intensity of 100mW cm^(-2) is used to test this new type of solar cell. The light falls on an A1 photoelectric cathode of area 1cm^(-2).

1)   Assuming every photon is converted to an electron, how much electrical current flows in this device ?

Explanation / Answer

we need to figure out how many photons occur every second for 100mw
so, the energy of one photon is :

E=hf=6.626x10-34(3x108/248x10-9)

E=8.015x10-19 joules

so the amount of photons that hit the metal every second is

n=100x10-3/8.015x10-19

n=1.247x1017 photons/sec=1.247x1017 electrons/sec

Now we look at the definition of current:

I=Q/t

Q is going to the number of electrons multiplied by the charge of an electron

I=1.247x1017(1.602x10-19)/1

I=.01999 amps

Hope that helps

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.