The approach is:
1) What is the purpose of the light bulb? Provide light.
2) Difference between coiled and uncoiled? Light scattered
differently.
The assumption made in this question such that
i. votage, current, resistence, other paramenters unchange.
iii. only difference comparision is coiled and uncoiled. as shown
in my diagram (look out for it)
Using elimination method, option (d) will be out. Increase in
length, increases the resistence. - as mentioned by SBS n SMRT.
The answer is not option (c), as the main purpose of a light
bulb is to produce light. Incandescent light bulb, to me, is not an
energy-saving light bulb. Hugh amount of energy is lost as
heat.
Option (a) is not true too. As mentioned by SBS n SMRT, "current
have nothing gotta do with coils". Actually it has, but it's
dependant on the source of the electricity.
Option (b) seems to be the correct on after analyzing and
reasoning.
a - coiled
b - uncoiled
.
Summary:
Coiled filament tends to be emits more light due to the surface
area to length dimension compacted in the coiled as compared to
filament stretch straigth.
Hypothesis generated: No matter how long you extend figure b,
the light given off in terms of brightness (comparison with coiled
vs uncoiled) will never exceed figure a.
Option (b) seems to be the more 'right'
answer.
Gees.. this sec 2 physics question is general.... I didn't see
any quantitatives in this questions...
comments and opinion appreciated. Thank you.
Regards,
Chin Seng.