Awire of nichrome (a nickel-chromium-iron alloy commonly used in heating elements) is 1.3 m long and 1.6 mm2 in cross-sectional area. it carries a current of 3.2 a when a 2.0 v potential difference is applied between its ends. calculate the conductivity σ of nichrome. /ω · m

1.3 *10^6 Ω*m

Explanation: In order to explain this problem we have to use the following expression for the resistence:

R=L/(σ*A) where L and A are the length and teh area for the wire, respectively. σ is the conductivity of teh Nichrome.

Then, from mteh OHM law we have V=R*I so R=V/I=2/3.2=0.625 Ω

Finally we have:

σ=L/(R*A)=1.3/(0.625*1.6*10^-6)=1.3*10^6 Ω*m

heats surface water up

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m