Number of electrons leaving crystal surface. any help ?

In summary, the scanning tunnelling electron microscope measures a tiny electrical current of 0.30 pA (0.30 x 10-12 A) tunnelling out of the surface of a crystal. Using the definition of an Ampere (1 Coulomb/sec) and the fact that 1 Coulomb is equal to 6.24 x 1018 elementary charges, the number of electrons leaving the crystal surface per second can be calculated. The result is 1,872,000 electrons per second.
  • #1
CharS
5
0
number of electrons leaving crystal surface. any help :)?

1. A scanning tunnelling electron microscope (STM) measures a tiny electrical current tunnelling out of the surface of a crystal. The current is 0.30 pA (0.30 x 10-12 A).

Calculate the number of electrons per second leaving the surface of the crystal.



2. mass of an electron = 9.11 x 10-31 kg
charge of an electron = -1.6 x 100-19 C



3. I have no idea how to answer this. Thanks to anyone who has any tips or pointers :) or can show me how to work it out correctly! x
 
Physics news on Phys.org
  • #2


CharS said:
1. A scanning tunnelling electron microscope (STM) measures a tiny electrical current tunnelling out of the surface of a crystal. The current is 0.30 pA (0.30 x 10-12 A).

Calculate the number of electrons per second leaving the surface of the crystal.

2. mass of an electron = 9.11 x 10-31 kg
charge of an electron = -1.6 x 100-19 C

3. I have no idea how to answer this. Thanks to anyone who has any tips or pointers :) or can show me how to work it out correctly! x


Welcome to PF.

Neither the mass nor the charge is that useful for this. You need to look at the definition of an Ampere, which is 1 Coulomb/sec.

A Coulomb relates to a quantity of charges. Just look it up and calculate the rest.
Wikipedia said:
A coulomb is then equal to exactly 6.241 509 629 152 65 × 1018 elementary charges.
 
  • #3


thank you for your help :)

I looked it up before with little success!

so would the answer be = (0.30 x 10^-12) x (6.241 509 629 152 65 × 10^18)

??

i must look incredibly stupid! just never been taught this before, finding it really hard to learn myself x
 
  • #4


oh wait.

i think it's 0.30 x 10^-12/ 6.24150948×10^18

before was wrong. is that the correct calculation?x
 
  • #5


CharS said:
thank you for your help :)

I looked it up before with little success!

so would the answer be = (0.30 x 10^-12) x (6.241 509 629 152 65 × 10^18)

When you do the math it will be.

You can simplify the number of digits needed however:

(0.30 x 10-12) x (6.24 × 1018)
 
  • #6


so the answer is 1,872,000

i'm still struggling to understand how this works. thankyou for your help
 

1. What is the significance of the number of electrons leaving a crystal surface?

The number of electrons leaving a crystal surface can provide valuable information about the surface properties of the crystal, such as its electronic structure and reactivity.

2. How is the number of electrons leaving a crystal surface measured?

The number of electrons leaving a crystal surface is typically measured using techniques such as Kelvin probe force microscopy or photoelectron spectroscopy.

3. What factors can affect the number of electrons leaving a crystal surface?

The number of electrons leaving a crystal surface can be influenced by factors such as the crystal's surface composition, temperature, and exposure to light or other external stimuli.

4. How does the number of electrons leaving a crystal surface relate to its conductivity?

The number of electrons leaving a crystal surface is directly related to its conductivity. Higher numbers of electrons leaving the surface indicate a higher conductivity, while lower numbers indicate a lower conductivity.

5. Can the number of electrons leaving a crystal surface be controlled?

Yes, the number of electrons leaving a crystal surface can be controlled through various methods, such as changing the crystal's surface composition or applying an external voltage.

Similar threads

  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Classical Physics
Replies
28
Views
1K
  • Introductory Physics Homework Help
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
922
  • Introductory Physics Homework Help
Replies
5
Views
3K
  • Introductory Physics Homework Help
Replies
2
Views
8K
  • Introductory Physics Homework Help
Replies
1
Views
751
  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
6K
  • Introductory Physics Homework Help
Replies
4
Views
942
Back
Top