Radiometer

Imagine you're trying to decide which room in your house is the warmest by noticing where the cat prefers to nap. Just like how the cat instinctively chooses the sunniest spot for its warmth, a radiometer measures the power of electromagnetic radiation by responding to the energy it receives. In this analogy, the cat represents the radiometer, the sunny spot is the electromagnetic radiation, and the warmth felt by the cat equates to the radiometer's measurement of the power of this radiation.