Here is the law the electrical grid is built on: $\varepsilon = N\dfrac{\Delta\Phi}{\Delta t}$, read aloud epsilon equals N delta-phi over delta-t. $\varepsilon$ (epsilon) is the induced EMF in volts — EMF stands for electromotive force, which is a terrible name, because it is a voltage and not a force at all; $N$ is the number of turns, a bare count, and every turn adds its own voltage in series; $\Delta\Phi$ is the CHANGE in flux through one turn, in webers, where $\Delta$ (delta) means “the change in”; and $\Delta t$ is the time that change took, in seconds.

Read the formula as the sentence it is: a coil generates voltage only while the flux through it is CHANGING. Park a coil in the strongest steady field on Earth and it produces exactly zero. A generator is not a magnet near a coil; it is a magnet that will not hold still.

The tidiest case gets its own formula. Slide a straight conductor across a field and it sweeps out fresh area every second — a changing flux with the algebra already done: $\varepsilon = BLv$, epsilon equals B L v, with $B$ the field in teslas, $L$ the conductor's length in metres, and $v$ its speed across the field in metres per second. No constant, no turns, three multiplications. That is why an aircraft's wingtips sit at a fraction of a volt above each other as it flies through Earth's field — real, measurable, and completely useless.