# Optics: How much light required to heat water?

**1. The problem statement, all variables and given/known data**

How many grams of water could have its temperature raised by 1.13 °C by a mole of photons that have a wavelength of 510 nm?

**2. Relevant equations**

E=hf

λf=c

**3. The attempt at a solution**

(3×10^8) / (510 x 10^-9) = 5.88 x 10^14 Hz

multiply by Planck’s constant to get E= 3.8977×10^-19 J/photon.

Now multiply by avogadro’s number to get 234719J

234,719J = m (4.18J/g C)(1.13 C)

m = 49693g

supposedly not the correct answer. I don’t know the correct answer but the input thing for online homework tells me it wants 3 significant figures in grams and since you can’t enter any powers of ten the answer must be less than a kg.

Any ideas?

http://ift.tt/PBdEbN

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