Question

1. if you use a dimmer switch to reduce the brightness of a light bulb, which property of the light wave are you primarily changing? why?

Explanation:

The problem is about light waves and a dimmer switch affecting brightness. In physics (a subfield of Natural Science), the brightness of a light wave is related to its amplitude (or intensity, which is related to the square of amplitude). A dimmer switch reduces the current, which reduces the power (and thus the intensity/amplitude) of the light wave. Frequency (related to color) and wavelength don't change with brightness adjustment here. So the primary property changed is amplitude (or intensity), as brightness depends on the amount of energy per unit area per unit time (intensity), which is linked to amplitude for light waves.

Answer:

The property primarily changed is the amplitude (or intensity) of the light wave. Because the brightness of a light wave is related to its intensity (power per unit area), and intensity is proportional to the square of the amplitude of the light wave. A dimmer switch reduces the electrical power supplied to the bulb, which in turn reduces the intensity (and thus the amplitude - related to the energy of the light wave), decreasing the brightness. The frequency (and related wavelength, for a given medium) of the light from the bulb remains essentially constant as it's determined by the nature of the light - emitting process (e.g., for an incandescent bulb, the thermal radiation spectrum's peak is related to temperature, but dimming mainly changes power, not the fundamental frequency - related color - temperature shift in a major way for typical dimming; for other bulbs like LEDs, the frequency is fixed by the device's design). So the key change for brightness is in amplitude/intensity.