Question

When paper is wrapped over wood it catches

Answer 1

it catches fire ..........

Answer 2

The paper in the side of wood catch fire but nothing happens to the side of brass.

The reason for this is given below that picture... Brass is the good conductor of heat whereas wood is not. So, the heat sent to the paper on copper is absorbed by copper so that the paper don't reach the ignition temperature or temperature in which it gets heated.

There is another example of pouring water into filter paper and heating. In this case, till water fully evaporates, the filter paper don't catch fire. Bcoz water (may be impure) is a good conductor of heat.