the human eye and the colourful world — Science STD 10 — Question
Gujarat BoardEnglish MediumSTD 10Sciencethe human eye and the colourful world3 Marks
Question
Which law gives relation between potential difference across a metallic wire and current through it ? Describe it in brief.
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Answer
Ohm's law gives relation between potential difference across a metallic wire and current through it. This law was deduced experimentally by German physicist, George Simon Ohm. It can be stated as follows. °Statement :
→ "Potential difference $(V)$ across a current carrying metallic wire is directly proportional to current $(I)$ flowing through it, provided temperature of wire remains constant."
→ Mathematically, $V \propto I$
$\therefore \quad \frac{V}{I}=\text { constant }$
→ Here ratio $\frac{V}{I}$ remains constant for a given metallic wire at a given temperature. Such a constant ratio is called "resistance" of a given metallic wire, shown by symbol $R$. It is the property of a conductor to resist the flow of charges through it. Thus,
$\frac{V}{I}=R$
→ Electrical component having resistance is called "resistor"
→ $SI$ unit of resistance is ohm, shown by symbol $\Omega$.
→ Equation $(2)$ gives mathematical form of Ohm's law. Writing $S I$ units in equation $(2)$,
$\frac{\text { volt }}{\text { ampere }}= Ohm$
→ Using symbols, $\Omega=\frac{V}{A}=V A^{-1}$
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