Question

In an element, let w be the energy, and q be the charge, what is the voltage across the element?
1. w + q
2. w - q
3. w × q
4. \(\frac{{dw}}{{dq}}\)

Answer 1

Correct Answer - Option 4 : \(\frac{{dw}}{{dq}}\)

One Volt is equivalent to one Joule per Coulomb.

If the electrical potential difference between two points is 1 volt, then one Coulomb of charge will gain 1 joule of potential energy when moved between those two points, i.e.

\(1Volt = \frac{{1Joule}}{{1Coulomb}}\)

∴ The voltage across the element is defined as the rate of change of energy per unit charge, i.e. 

\(V=\frac{{dw}}{{dQ}}\)