Ignition temperature of paper is very low. When we try to ignite a paper, all the heat is absorbed by the paper and when it reaches its ignition temperature, it catches fire.
But when the paper is wrapped around a aluminium pipe, aluminium being a good conductor of heat, absorbs most of the heat...
A quick search did not prove very fruitful. Glass is not transparent to IR, as you can see in the man's glasses in the picture above, as well as at 0:20 in this video. However, at 0:52 in the same video you can see that glass does reflect IR to some extent (when the hand is on the same side as...
A real object is one which is practically present in front of an Optical Instrument.
A virtual object is an an image produced by an optical instrument which is made incident on any other optical instrument.
Suppose you have two mirrors. You place an object in front of one mirror. The mirror...