The adjective cumulative describes the total amount of something when it's all added together. Eating a single chocolate doughnut is fine, but the cumulative effect of eating them all day is that you'll probably feel sick. If something is cumulative, it is heaped together so it can be counted up to get a total number. The cumulative snowfall for the whole winter isn't just the amount of snow that fell in one month, but rather the number of inches that fell every month that winter to get the total, cumulative, amount.
Light has a constant speed through a given substance. For example, it always travels at a speed of approximately 3 x 10 8 metres per second in a vacuum. This is actually the speed that all electromagnetic radiation travels-not just visible light.
The Electromagnetic Spectrum The electromagnetic (EM) spectrum is the range of all types of EM radiation. Radiation is energy that travels and spreads out as it goes â the visible light that comes from a lamp in your house and the radio waves that come from a radio station are two types of electromagnetic radiation. The other types of EM radiation that make up the electromagnetic spectrum are microwaves, infrared light, ultraviolet light, X-rays and gamma-rays.