I. The rate of change of potential between two points with respect to distance is the definition of the electric field strength. Mathematically, the electric field E is the negative gradie

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i. The rate of change of potential between two points with respect to distance is the definition of the electric field strength. Mathematically, the electric field $\vec{E}$ is the negative gradient of the electric potential $V$, i.e., $\vec{E} = -\nabla V$. In one dimension, this simplifies to $E = -\frac{dV}{dr}$.

• B) electric field

ii. In a thermocouple, the thermoelectric electromotive force (e.m.f.) varies with temperature. It increases with temperature, reaches a maximum value at a specific temperature, and then decreases, eventually becoming zero and reversing its direction. The temperature at which the thermoelectric e.m.f. becomes maximum is known as