What did the Magdeburg experiment demonstrate about air pressure that the horses could not get sufficient traction to pull the hemispheres apart

that atmospheric pressure on the earth's surface has tremendous force

that the vacuum inside the two attached hemispheres has tremendous suction

that horses are not intelligent enough to understand how to defeat atmospheric pressure

pregnancy happens more and more

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.