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HW Key _4 S problems part b

# HW Key _4 S problems part b - S12 Microwave ovens use...

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S12. Microwave ovens use radiation with a frequency of 2.45 x 10 9 s -1 (or 2.45 gigzhertz, the same frequency as cordless phones and wireless Ethernet connections). Calculate the number of such photons that must be absorbed to raise the temperature of 100.0 g of water from 15 °C to its boiling point, 100 °C, assuming it takes 4.2 J/g to raise the temperature of water by 1 degree C. The energy of each photon is given according to E=h ν = (6.626 × 10 34 Js)(2.45 × 10 9 s 1 ) = 1.62 × 10 24 J/photon The energy change to heat the water is the heat absorbed E=(4.2 J/g°C)(100.0 g)(100-15 °C)=3.57 × 10 4 J The number of photons is the ratio of these two numbers 3.57 × 10 4 J 1.62 × 10 24 J/photon = 2.2 × 10 28 photons S13. In the Bohr model of the hydrogen atom, precisely what is quantized? In the Bohr model, the angular momentum is the fundamental property that is quantized. Quantization of angular momentum then leads to other properties being quantized, including the radius of electron orbit and the energy of the states. S14. The treatment of the particle in a one-dimensional box can be extended to a two-dimensional box of dimensions L x and L y yielding the following expression for energy: E = h

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