In the ratio of the concentration of electrons that of holes in a semiconductor is 7/5 and the ratio of currents is 7/4 then what is the ratio of their drift velocities?

  • Option 1)

    4/7

  • Option 2)

    5/8

  • Option 3)

    4/5

  • Option 4)

    5/4.

 

Answers (1)
D Divya Saini

As we learnt in

Electrical Conductivity (σ) -

\sigma =e \left (n_{e}\mu _{e}+n_{\lambda}\mu _{h} \right )
 

- wherein

n_{e}= electron \: density

n_{h}= hole \: density

\mu _{e}= mobility \: of \: electron

\mu _{h}= mobility \: of \: holes

 

 I=nV_{d}\ eA

V_{d}\rightarrow drift velocity

\frac{I_{e}}{I_{h}}=\frac{n_{e}}{n_{h}}.\frac{V_{d,e}}{V_{d,h}}

\Rightarrow\ \; \frac{7}{4}=\frac{7}{5}.\frac{V_{d,e}}{V_{d,h}}

\Rightarrow\ \; \frac{V_{d,e}}{V_{d,h}}=\frac{5}{4}

Correct option is 4.

 


Option 1)

4/7

This is an incorrect option.

Option 2)

5/8

This is an incorrect option.

Option 3)

4/5

This is an incorrect option.

Option 4)

5/4.

This is an correct option.

Exams
Articles
Questions