Question

An unlit match is held near ( not touching) to an extremely hot bunsen flame. The match does NOT get hot enough to light because
a. the flame is not hot enough b. air is a bad conductor of heat
c. the match head reflects radiation d. the flame does not radiate any heat sideways.

what is the ans ?? :S

Answer 1

i hate this kind of ambiguous questions!!! conduction, convection, radiation, so air is a bad conductor of heat but if convection of flame was high enough match would be lit, match as every object reflects some portion of radiation cause otherwise you couldnt see her and flame dose radiate just question is how much....

Answer 2

I agree that the question is ambiguous but I believe the best answer is b.

Answer 3

I would answer: flame is not hot enough or match is not close enough, because it is a case where heat is transmitted by radiation.
I agree with Kryten and Shane: very ambiguous wording.

Answer 4

I considered "a" as well but it says "extremely hot bunsen flame"....which drove me to d. It's anyone's guess...the question stinks.

Answer 5

the answer is d because the bunsen burner is made to focus the heat it generates in the direction it is pointing.

Answer 6

b. air is a bad conductor of heat

Answer 7

air is bad conductor of heat, if air is replaced by any good conductor of heat like copper the match will light up.

Answer 8

Let's take a closer look.

Obviously, the flame, in and of itself, is hot enough to light a match. It cannot be a.

Air is a relatively poor conductor of heat. Consider that air has a conductivity value of roughly 0.035, while copper, like most metals, is a good conductor of heat with a conductivity value of roughly 400.

Perhaps the match head does reflect radiation (in fact, it probably does reflect at least a very small portion) but a good indicator reflectivity is that is appears shiny. This may be a valid answer, but is it the best answer? Probably not.

The wording of d is very strong, "the flame does NOT radiate ANY heat sideways." This must be false. Put a thermometer next to a flame and you are sure to see an increase in temperature. Radiation is very diffuse by nature, and since the entire flame front is hotter than the surrounding air, it will likely radiate in all directions.

Answer 9

@eashmore: My thoughts exactly...especially about the wording of d.

Answer 10

@Shane_B Your intuition is correct by my opinion. This is a common theme with multichoice questions, especially at the college level. The answer is not always clear, ambiguity is always present, and critical thinking is a must.

@fatima1 I hope my thought process here can prove useful in future questions.

Answer 11

@eashmore yes thanks a lot

Answer 12

and thanks to all other people who replied it