KCET · Physics · Current Electricity
The electric current flowing through a given conductor varies with time as shown in the graph below. The number of free electrons which flow through a given cross-section of the conductor in the time interval \(0 \leq t \leq 20 \mathrm{~s}\) is
- A \(3.125 \times 10^{19}\)
- B \(1.6 \times 10^{19}\)
- C \(6.25 \times 10^{18}\)
- D \(1.625 \times 10^{18}\)
Answer & Solution
Correct Answer
(A) \(3.125 \times 10^{19}\)
Step-by-step Solution
Detailed explanation
Total charge flowing the cross-section of the conductor is equal to area under I-t graph.
\(\therefore Q=\frac{(100+300)}{2} 10 \times 10^{-3}+(20-10) \times 300 \times 10^{-3}\)
\(=1+3=4 C\)
Since, \(Q=n e\)
\(\therefore \quad n=\frac{Q}{e}=\frac{4}{1.6 \times 10^{-19}}=3.125 \times 10^{19}\)
\(\therefore Q=\frac{(100+300)}{2} 10 \times 10^{-3}+(20-10) \times 300 \times 10^{-3}\)
\(=1+3=4 C\)
Since, \(Q=n e\)
\(\therefore \quad n=\frac{Q}{e}=\frac{4}{1.6 \times 10^{-19}}=3.125 \times 10^{19}\)
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