Question

How does a smartphone touchscreen detect the location of a finger based on electrostatic principles?

Options

• By calculating the mechanical pressure exerted on equipotential surfaces.

• By generating a constant magnetic flux perpendicular to the screen.

• By measuring tiny changes in electric potential across a grid.

• By monitoring thermal expansion of equipotential lines.

Answer 1

A phone's touchscreen detects the location of a finger by measuring tiny changes in electric potential across a grid, where the direction in which potential drops fastest corresponds to the electric field.