the human eye and the colourful world — Science STD 10 — Question
Gujarat BoardEnglish MediumSTD 10Sciencethe human eye and the colourful world3 Marks
Question
How is electric current expressed ? Describe about its $SI$ unit also.
✓
Answer
Electric current is expressed as net amount of electric charge passing through the cross - section of a conductor in unit time.
- In other words, electric current is the time rate of flow of electric charge.
$\sim$ If net charge $Q$ passes through the cross-section of a given conductor in time $t$ then electric current $I$ passing through that conductor is given by,
$I=\frac{Q}{t}$
$SI$ unit of electric charge is coulomb, shown by symbol $C$.
$SI$ unit of electric current is ampere, shown by symbol $A$.
⇒ From above equation
$1 A=1 \frac{C}{s}$
⇒ Definition of $1$ ampere :
⇒ In equation $(1)$, if $Q=1 C$ and $t=1 s$ then $I=$ $1 \frac{C}{s}=1 A$ and so $SI$ unit of electric current can be defined as follows.
⇒ "When net electric charge passing through cross-section of a given conductor in $1 s$ is $1 C$ then electric current passing through that conductor is said to be $1 . A$."
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