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Potential Difference, Ohm's Law and Resistance
Unit of Potential Difference
The SI unit of potential difference is the same as that for e.m.f., i.e. the volt. We define the volt as follows:
The potential difference (p.d.) between two points in a conductor is 1 volt if 1 joule of energy is converted from electrical to other forms when 1 coulomb of positive charge flows through it.
Answer:
The charge, Q = 5C
Potential difference, V = 10V
Energy, E = ?
\begin{gathered}
V = \frac{E}
{Q} \hfill \\
(10) = \frac{E}
{{(5)}} \hfill \\
E = 5 \times 10 = 50J \hfill \\
\end{gathered}
Ohm's Law
The current flowing in the metallic conductor is directly proportional to the potential difference applied across it’s ends, provided that the physical conditions ( such as temperature ) are constant.
Formula:
Any other conductors, other than metallic conductors, which obey Ohm’s Law are described as Ohmic conductors.
Answer:
(In this question, 2 physical quantities are given, they are the "240V" and "80Ω". The question doesn't tell what quantites they are. However we can recognise these quantities from its unit. Ω is the unit of resistance whereas V is the unit of potential difference.)
Resistance, R = 80Ω
Potential difference, V = 240V
Current, I = ?
(240) = I(80)
I = 3A
Resistance
The resistance R of a material is defined as the ratio V : I, where V is the potential difference across the material and I is the current flowing in it.
Unit:
The SI unit of resistance is the ohm (Ω). One ohm is the resistance of a material through which a current of one ampere flows when a potential difference of one volt is maintained.
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