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5. Find the current density in an electron beam if the number of electrons passing per second through the cross-section is [tex]6 \times 10^6[/tex]. The area of the electron beam is [tex]10^{-6} \, m^2[/tex].

Answer: [tex]9.6 \times 10^3 \, \text{A/m}^2[/tex]


Sagot :

Sure, let’s solve this problem step by step.

1. Understanding the given data:
- Number of electrons per second, [tex]\( n = 6 \times 10^6 \)[/tex] electrons/s
- Cross-sectional area of the electron beam, [tex]\( A = 10^{-6} \, \text{m}^2 \)[/tex]
- Charge of one electron, [tex]\( e = 1.6 \times 10^{-19} \, \text{C} \)[/tex]

2. Calculate the total current (I):
The current ([tex]\( I \)[/tex]) can be calculated by multiplying the number of electrons passing per second by the charge of one electron.
[tex]\[ I = n \times e \][/tex]
Plugging in the values:
[tex]\[ I = (6 \times 10^6) \, \text{electrons/s} \times 1.6 \times 10^{-19} \, \text{C/electron} \][/tex]
[tex]\[ I = 9.6 \times 10^{-13} \, \text{A} \][/tex]

3. Calculate the current density (J):
Current density ([tex]\( J \)[/tex]) is defined as the current per unit area. It can be calculated by dividing the current by the cross-sectional area.
[tex]\[ J = \frac{I}{A} \][/tex]
Plugging in the values:
[tex]\[ J = \frac{9.6 \times 10^{-13} \, \text{A}}{10^{-6} \, \text{m}^2} \][/tex]
[tex]\[ J = 9.6 \times 10^{-7} \, \text{A/m}^2 \][/tex]

4. Conclusion:
The current in the electron beam is [tex]\( 9.6 \times 10^{-13} \)[/tex] amperes, and the current density is [tex]\( 9.6 \times 10^{-7} \)[/tex] amperes per square meter.

Thus, the solution states that the current density in the electron beam is [tex]\( 9.6 \times 10^{-7} \, \text{A/m}^2 \)[/tex].