When two light beams of wavelengths 1and fall on a metal surface, they produce photoelectrons with energies 115 eV and 254 eV respectively. Estimate the numerical value of the Planck constant.

You had some formatting error when you posted your question. What are the wavelengths of the two beams? You're going to use the formula: E = hf E is energy h is Planck's constant (which is what you're solving for) f is frequency You'll notice that we we're given the energy (115 eV and 254 eV) but we don't know the frequencies. You use another formula to calculate the frequency \( c = \lambda f\) c is the speed of light which is a constant 3.0*10^8 m/s \(\lambda\) is the wavelength which is given to you in your question f is the frequency You could plug that into the first formula to get \(\sf E = \dfrac{h c}{\lambda}\) You have values for everything besides 'h' which is what you're trying to solve for

Let me know how far you get in solving your problem or if you'd like any further clarification :)

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