Radiation and Convection?

Question

1)Why is the freezer at the top in most refrigerrators?
2)Freezers in supermarkets are not covered. How does the food in the freezer stay frozen?
3)Heat energy from the sun reaches us in the form of _______ (__________) .
4)How do snakes detect the presence of a rat nearby?
By picking ______ as all warm blooded animals emit heat in form of ________ .
5) Infra-red raidiation travels at the speed of __________.
6) Name 3 best radiators of heat.
7) Name 3 poorest radiators of heat.
8) Best radiators are also ______ of radiant heat. They also ______ of heat.
9) Poorest radiators are also ________ of heat. They also _______ of heat.
10) Any body with ______ than room temperature will radiate heat to the surroundings.

PLEASE help me ans. as many of my quries as possible! THANKS LOADS! I REALLY APPRICIATE IT!

Answer 1

1. Someone said heat rises - not true. Warm air is lighter than cold air, so warm air rises. The evaporator of the fridge being on top will give a more even 'cold' distribution. If the evaporator was on the bottom, the bottom of the fridge would always be colder than the top.
2. Cold air is heavier than warm air. If the freezer is open on top, the cold air will not escape. If the freezer is upright, with no doors, the freezer will lose all of it's 'cold' air, it will spill out of the freezer.
3. Radiation
4. Pit vipers have an infrared sensor. It picks up the heat generated by the rat's body heat, in the form of radiation.
5. speed of light.

Answer 2

You need to learn a couple of fundamental principles:

1. Heat rises.
2. Electromagnetic radiation has both wave-like and particle-like properties. The particles are called photons and they span a very large range of frequency and energy.
3. The best radiators are the ones whose atoms cannot move around very much.
4. The poorest radiators are the ones whose atoms can move around a lot.
5. Nature abhors a vacuum AND a temperature DIFFERENCE.

Answer 3

Beats me too! Why dont ya try wikipedia.org

Answer 4

I don't come here to do exams