Answer:0.667 N
Explanation:
Given
It is noticed that Frictional Force is 0.2 N
Coefficient of kinetic Friction ![\mu _k=0.3](https://tex.z-dn.net/?f=%5Cmu%20_k%3D0.3)
We know Friction Force is given by
![f_r=\mu _k\times Normal\ reaction](https://tex.z-dn.net/?f=f_r%3D%5Cmu%20_k%5Ctimes%20Normal%5C%20reaction)
therefore
![0.2=\mu _k\times N](https://tex.z-dn.net/?f=0.2%3D%5Cmu%20_k%5Ctimes%20N)
![0.2=0.3\cdot N](https://tex.z-dn.net/?f=0.2%3D0.3%5Ccdot%20N)
![N=\frac{0.2}{0.3}](https://tex.z-dn.net/?f=N%3D%5Cfrac%7B0.2%7D%7B0.3%7D)
![N=0.667 N](https://tex.z-dn.net/?f=N%3D0.667%20N)
The answer would be, "Granite".
Answer:
Total 3 holes are available for conduction of current at 300K.
Explanation:
In order to develop a semiconductor, two type of impurities can be added as given below:
- N-type Impurities: Pentavalent impurities e.g. Phosphorous, Arsenic are added to have an additional electron in the structure. Thus a pentavalent impurity creates 1 additional electron.
- P-type Impurities: Trivalent impurities e.g. Boron, Aluminium are added to have a positive "hole" in the structure. Thus a trivalent impurity creates 1 hole.
Now for estimation of extra electrons in the impured structure is as
![N_{electrons-free}=n_{pentavalent \, atoms}\\N_{electrons-free}=4\\](https://tex.z-dn.net/?f=N_%7Belectrons-free%7D%3Dn_%7Bpentavalent%20%5C%2C%20atoms%7D%5C%5CN_%7Belectrons-free%7D%3D4%5C%5C)
Now for estimation of "holes" in the impured structure is as
![N_{holes}=n_{trivalent \, atoms}\\N_{holes}=7\\](https://tex.z-dn.net/?f=N_%7Bholes%7D%3Dn_%7Btrivalent%20%5C%2C%20atoms%7D%5C%5CN_%7Bholes%7D%3D7%5C%5C)
Now when the free electrons and "holes" are available in the structure ,the "holes" will be filled by the free electrons therefore
![N_{holes-net}=N_{holes}-N_{electrons-free}\\N_{holes-net}=7-4\\N_{holes-net}=3](https://tex.z-dn.net/?f=N_%7Bholes-net%7D%3DN_%7Bholes%7D-N_%7Belectrons-free%7D%5C%5CN_%7Bholes-net%7D%3D7-4%5C%5CN_%7Bholes-net%7D%3D3)
So total 3 "holes" are available for conduction of current at 300K.