Upon being struck by 240 nm photons, a material ejects electrons with a maximum

Question

Upon being struck by 240 nm photons, a material ejects electrons with a maximum kinetic energy of 3.22 eV. What is the work function of this material? 1.96 eV 1.65 eV 2.27eV 2.59eV A helium-neon laser emits light at 632.8 nm. If the laser emits 1.99 Times 10^17 photons/second, what is its power output in mW? 40.6 mW 62.5 mW 31.3mW 50.0 mW A hydrogen atom and a neutron fuse to form deuterium. If the energy released is 3.6 Times 10^-13 J, what is the mass of the deuterium? Take the H atom nucleus as a single proton.

Explanation / Answer

27) energy of photon = hc/lemda = (4.14 x 10^-15 x 3 x 10^8) / (240 x 10^-9) eV

= 5.18 eV

work function = photon energy - maximum kinetic energy of electron

= (5.18 - 3.22)eV = 1.96 eV

28) power output = number of photon per second x energy of photon

= (1.99 x 10^17) x (hc/lemda)

= (1.99 x 10^17) x ((6.26 x 10^-34 x 3 x 10^8)/(632.8 x 10^-9)) J

= 59.1 mW

29) mass of deuterium = mass of proton + mass of neutron - mass of equivalent released energy

mass of equivalent released energy = (3.6 x 10^-13) / c^2 =  (3.6 x 10^-13) / (9 x 10^16) kg

= 4.0 x 10^-30 kg

mass of deuterium = (1.672 + 1.675 + 0.004) x 10^-27 kg

= 3.351 x 10^-27 kg

    3.4 x 10^-27 kg

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