Laws and principles tell you about different phenomena in physics.

Automatic transfer switches ensure power continues to flow through buildings.

The lifting force tells you how gases and liquids rise.

Solar insolation lets you figure out how sunlight radiates.

Parallel circuits distribute current across branches.

Calculate illuminance to measure how much light falls on a surface.

Use a rectifier to control how current flows in a circuit.

While they may be used interchangeably, scales and balances generally measure different quantities.

Coal gasification comes with a price.

Magnetic fields tell you how a magnetic force would distribute itself around objects.