How many electrons per second pass through a cross-section of copper wire carrying `10^(-16)` A current ?

Explanation

To find out how many electrons pass through a cross-section of a copper wire carrying a current of \(10^{-16}\) A, we can follow these steps:

### Step 1: Understand the relationship between current, charge, and time
The current \(I\) is defined as the charge \(Q\) passing through a cross-section of the wire per unit time \(t\):
\[ I = \frac{Q}{t} \]
Where:
- \(I\) is the current in amperes (A),
- \(Q\) is the charge in coulombs (C),
- \(t\) is the time in seconds (s).

### Step 2: Calculate the charge passing per second
Since we are interested in the number of electrons passing per second, we can rearrange the formula to find \(Q\) when \(t = 1\) second:
\[ Q = I \times t \]
Substituting \(I = 10^{-16}\) A and \(t = 1\) s:
\[ Q = 10^{-16} \, \text{C} \]

### Step 3: Determine the charge of a single electron
The charge of a single electron \(e\) is approximately:
\[ e = 1.6 \times 10^{-19} \, \text{C} \]

### Step 4: Calculate the number of electrons passing per second
To find the number of electrons \(N\) passing through the wire per second, we can use the formula:
\[ N = \frac{Q}{e} \]
Substituting the values we have:
\[ N = \frac{10^{-16} \, \text{C}}{1.6 \times 10^{-19} \, \text{C/electron}} \]

### Step 5: Perform the calculation
Calculating \(N\):
\[ N = \frac{10^{-16}}{1.6 \times 10^{-19}} = \frac{10^{-16}}{1.6} \times 10^{19} = 6.25 \times 10^{2} \approx 625 \]

### Final Answer
Thus, the number of electrons passing through a cross-section of the copper wire per second is approximately **625**.

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