7. Why do some bulbs
heat up more than others?

Bulbs that heat a gas or a filament will heat up more than other light sources.

Explanation:  

Incandescent bulbs are consist of thin wire known as filament which converts electric current into light. These filaments are made up of tungsten metal. The filaments gets hot due to the passage of electric currents which turns the bulb up. Bulb starts glowing and produce light then.

There are many ways to convert electricity into light that is why some bulbs heat up more than others. Some of then are very efficient (converts electricity to light mainly) while others are less efficient (converts electricity to light as well as produce plenty of heat).  

For example:

if they have a finite resultant

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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