Question about the photoelectric effect (1 Viewer)

[toprun91]

I know about the photoelectric effect that when a metal is hit with a electromagnetic wave it releases electrons. But were does it release the electrons. Is it into the air?

 

[Nuendo]

It happens in a vacuum. Once the photoelectrons are emitted from the metal surface (the photocathode), they accelerate towards the anode (using the kinetic energy provided by the photons. ie, KE = hf - work function).

 

[mwatts]

do you need to be able to calculate the kinetic energy of the photoelectrons?

 

[Nuendo]

do you need to be able to calculate the kinetic energy of the photoelectrons?

I don't think so, but it would help in terms of understanding the concept. I have seen HSC/Trial questions that ask about Einstein's contribution to quantum mechanics, which involves photons and the energy they carry (E=hf), and how that energy is distributed (ie, that energy is used to emit the electrons as well as provide the kinetic energy to travel towards the anode).

 

[toprun91]

I don't think so, but it would help in terms of understanding the concept. I have seen HSC/Trial questions that ask about Einstein's contribution to quantum mechanics, which involves photons and the energy they carry (E=hf), and how that energy is distributed (ie, that energy is used to emit the electrons as well as provide the kinetic energy to travel towards the anode).

are you sure you dont need to know it there is a dot point saying

• Solve problems and analyze information using:
  
  

  
  and
  

  

 

[Nuendo]

are you sure you dont need to know it there is a dot point saying

• Solve problems and analyze information using:
  
  

  
  and
  

  

I stand corrected, maybe we do have to know it...just learn it to be safe.

By the way, that dot point is a little misleading. Not only do you have to know how to work E=hf, but also E=hc/lambda and E=1/2mv^2. You might also be asked to use some things on the data sheet like the mass of an electron or the value of 1eV etc, to solve questions.