Question

A beggar wrapped himself with a few layers of newspapers on a cold winter night. This helped him to keep himself warm because:
A) Friction between the layers of newspaper produces heat.
B) Air trapped between the layers of newspaper is a bad conductor of heat.
C) Newspapers are a conductor of heat.
D) Newspapers are at a higher temperature than the temperature of the surroundings.

Answer 1

To solve this we must know that the beggar will feel cold only if the outer temperature gets transferred through the layers of the newspaper. If newspaper is a bad conductor then no heat will be transferred from the surrounding to the body.

Complete answer:
A beggar wrapped himself with a few layers of newspapers on a cold winter night. When he wrapped the layers of newspaper, air got trapped between those layers. We know that air is an indigenous gaseous component of the atmosphere. Air is made up of atoms which are neutral in nature. The air molecules do not have any predefined path or shape and thus, the air molecules are in a constant motion and revolve in a zigzag manner.

To transfer the cold wind from the atmosphere to the body the air molecules should serve as a medium to transfer the heat from one point to another point. Also, the air molecules should be in continuous contact.

But the air molecules are not in a continuous contact and thus, the air trapped between the layers of newspaper does not conduct the heat. Thus, the layers of newspaper helped beggar to keep himself warm because the air trapped between the layers of newspaper is a bad conductor of heat.

Thus, the correct answer is option (B) air trapped between the layers of newspaper is a bad conductor of heat.

Note: Heat is transferred from one point to another point through three different processes conduction, convection and radiation. The materials that allow heat to flow through it without any resistance are known as good conductors of heat and the materials that do not allow heat to flow through are known as poor conductors of heat.