Question

The inside of an oven is at a temperature of 200° C (392° F). You can put your hand in the oven without injury as long as you don’t touch anything. But since the air inside the oven is also at 200° C, why isn’t your hand burned just the same?

Short answer

You can put your hand in the oven for a short period without injury as long as you don’t touch anything and the hand is not burned because of the lesser density, less number of particles available, and poor conductivity of air.

Step-by-step solution

Given data

You can put your hand in the oven for a short period without injury as long as you don’t touch anything and the hand is not burned because of the lesser density, less number of particles available, and poor conductivity of air.

Explanation of not burning of hand inside the oven in the air due to less density

The inside of the oven is made of solid conducting material, and the air is in gas form.

Air possesses a tiny amount of thermal energy, and its thermal conductivity is very poor.

Air has a density significantly less than solid. So for a given volume of the system, when we put our hands in the oven, we are touching less particle that can transfer heat to our body compared to the number of particles we are touching if we touch anything in the oven. It takes time for less number of particles to transfer the same amount of thermal energy to our hand. If we keep our hands in the oven for a more extended period, we will feel the burn.

Explanation of not burning of hand inside the oven in the air due to poor conductivity

Another reason that may be given here is air is a very poor conductor of heat. Air molecules are at a finite distance, and they don’t interact until they have a specific environment provided to them. But solids have particles so close to each other that their compact structure helps transfer the heat effectively.

Thus, You can put your hand in the oven without injury as long as you don’t touch anything and the hand is not burned.