Question

Ten million electrons pass from point P to point Q in one micro second. The current and its direction is?

• A. $1.6\times {10}^{-14}A,$ from point P to point Q
• B. $3.2\times {10}^{-14}A$, from point P to point Q
• C. $1.6\times {10}^{-6}A$, from point Q to point P
• D. $3.2\times {10}^{-12}$A, from point Q to point P

Answer 1

The correct option is C $1.6\times {10}^{-6}A$, from point Q to point P

Here, number of electron, $n=10000000={10}^7$

Total charge on ten million electrons is

Q$=$ne[Where e$=1.6\times {10}^{-19}$C]

$={10}^7\times 1.6\times {10}^{-19}C=1.6\times {10}^{-12}$C

Time taken by ten million electrons to pass from point P to point Q is t$=$I $\mu$s$={10}^{-6}$s

The current

$I=\frac{Q}{t}=\frac{1.6\times {10}^{-12}}{{10}^{-6}}=1.6\times {10}^{-6}$A

Since the direction of the current is always opposite to the direction of flow of electrons. Therefore due to flow of electrons from point P to point Q the current will flow from point Q to point P.