Photo electric effect problem

In summary, the attempt at a solution involved converting the given values for energy and wavelength into SI units, and using the equation E=Ek-W to calculate the maximum kinetic energy (Ek) of ejected electrons. However, an error was made in the conversion of the work function from eV to Joules, resulting in a incorrect answer of -3.68*10^10eV. The correct answer is 2.10eV.
  • #1
mss90
29
0

Homework Statement


A magnesium surface has a work.func of 3.68eV. El.mag. waves with wavelenght of 215nm strike the surface and eject electrons. Find the max Ek of the ejected electrons in eV.

Homework Equations


E=Ek-W <=> Ek=(hc/lambda) - W

The Attempt at a Solution


I convert eV to J and nm to m but i get -3.68*10^10eV, but the answer is suppoused to be 2.10eV.
I even re did it but got the same answer, where em I going wrong?

Thanks
 
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  • #2
Hello.
In order to see where you are going wrong, we need to see your entire calculation.
 
  • #3
Ek=(hc/lambda)-W

((6.63*10^-34)*(3*10^8))/(2.15*10^-7) - (5.888*10^-9)

(9.25*10^-19) - ( (5.888*10^-9) = -5.887*10^-9 J / (1.6*10^-19) = -3.68*10^10eV
 
  • #4
mss90 said:
Ek=(hc/lambda)-W

((6.63*10^-34)*(3*10^8))/(2.15*10^-7) - (5.888*10^-9)

(9.25*10^-19) - ( (5.888*10^-9) = -5.887*10^-9 J / (1.6*10^-19) = -3.68*10^10eV

Check the power of 10 for the work function expressed in Joules.
 
  • #5
ah ye, there we go. thanks :)
 

1. What is the photoelectric effect?

The photoelectric effect is the phenomenon where certain metals emit electrons when exposed to light. This occurs because the energy from the light is transferred to the electrons, allowing them to overcome the binding forces of the metal and escape.

2. How does the intensity of light affect the photoelectric effect?

The intensity of light does not affect the photoelectric effect. Instead, it is the frequency of the light that determines the energy of the electrons emitted. Higher frequencies of light have more energy and can cause more electrons to be emitted from the metal surface.

3. What is the work function in the photoelectric effect?

The work function is the minimum amount of energy required for an electron to escape the metal surface. It is different for each type of metal and is a crucial factor in determining the energy of the emitted electrons in the photoelectric effect.

4. How does the photoelectric effect support the particle nature of light?

The photoelectric effect provides evidence for the particle nature of light, as it shows that light is made up of tiny packets of energy called photons. The energy of the emitted electrons is directly proportional to the frequency of the light, which supports the idea that light is made up of discrete particles.

5. What are some practical applications of the photoelectric effect?

The photoelectric effect has many practical applications, including solar panels, photodiodes, and photomultiplier tubes. It is also used in many devices such as cameras, scanners, and photocells. Additionally, the photoelectric effect plays a crucial role in the development of quantum mechanics and our understanding of the behavior of light and matter.

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