Calculating Current given the number of electrons and positive ions

In summary, to calculate current, you can use the equation I = (n*e)/(t), where I is the current in amperes, n is the number of electrons, e is the charge of one electron (1.6 x 10^-19 coulombs), and t is the time in seconds. The number of electrons is directly proportional to the current, meaning that as the number of electrons increases, the current also increases, and vice versa. It is not possible to calculate current without knowing the number of positive ions, as this is an essential part of the equation. The charge of an electron is a constant in the current equation and represents the amount of charge carried by each individual electron. This allows us to calculate the
  • #1
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Homework Statement



In a fluorescent tube of diameter 3 cm, 10 *1018 electrons and 2.5 * 1018 positive ions (with a charge of +e) flow through a cross-sectional area each second. What is the current in the tube?


Homework Equations


Current is I = (delta Q)/(deta T)



The Attempt at a Solution



delta t is given as 1 second, but how do u calculate the change in charge given this information?
 
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  • #2
Use the charge on the electron. Note that the positive ions will go the opposite way to the electrons, so you must add the two currents.
 
  • #3


I would approach this problem by first understanding the basic principles of current and charge. Current is defined as the rate of flow of electric charge, and is measured in units of amperes (A). Charge, on the other hand, is measured in units of coulombs (C).

In this scenario, we are given the number of electrons and positive ions flowing through the cross-sectional area of the fluorescent tube per second. This tells us the total amount of charge passing through the area per second. To calculate the current, we need to determine the change in charge over time.

To do this, we can use the equation for current: I = (delta Q)/(delta t). In this case, delta t is given as 1 second, so we just need to calculate the change in charge, delta Q.

Since we are given the number of electrons and positive ions, we can use the fact that each electron has a charge of -e and each positive ion has a charge of +e. This means that the total charge passing through the area per second is (10 * 10^18 * -e) + (2.5 * 10^18 * +e) = -7.5 * 10^18 e.

To convert this to coulombs, we can use the fact that 1 e = 1.602 * 10^-19 C. This gives us a total charge of -7.5 * 10^18 * 1.602 * 10^-19 C = -12.03 C.

Now, we can plug this value for delta Q into the equation for current: I = (-12.03 C)/(1 s) = -12.03 A.

We must also consider the direction of the current. Since the charge carriers in this scenario are both positive and negative, the overall current will be the sum of the individual currents, taking into account their direction. In this case, the negative charge carriers (electrons) will contribute a negative current, while the positive charge carriers (positive ions) will contribute a positive current. So, the overall current in the tube will be -12.03 A + 12.03 A = 0 A.

In conclusion, the current in the fluorescent tube is 0 A, given the number of electrons and positive ions flowing through the cross-sectional area per second. This result is not surprising, as the total charge passing through the area
 

1. How do you calculate current given the number of electrons and positive ions?

To calculate current, you can use the equation I = (n*e)/(t), where I is the current in amperes, n is the number of electrons, e is the charge of one electron (1.6 x 10^-19 coulombs), and t is the time in seconds.

2. What is the relationship between number of electrons and current?

The number of electrons is directly proportional to the current. This means that as the number of electrons increases, the current also increases, and vice versa.

3. Can you calculate current without knowing the number of positive ions?

No, the number of positive ions is an essential part of the equation for calculating current. Without this information, it is not possible to accurately determine the current.

4. How does the charge of an electron affect the calculation of current?

The charge of an electron (1.6 x 10^-19 coulombs) is a constant in the current equation. It represents the amount of charge carried by each individual electron, and allows us to calculate the total current based on the number of electrons present.

5. Can current be negative when using this formula?

Yes, current can be negative when using this formula. This indicates that the direction of the current is opposite to the direction of flow of electrons. In other words, the positive ions are moving in the direction of the current, while the electrons are moving in the opposite direction.

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