Photons with a frequency of 3000000000000000 Hz shine on a piece of aluminum (work function 4.1 eV)What is the energy of the ejected electrons? in JoulesWhat is the de Broglie wavelength of the ejected electrons? in nm.I am pretty much lost on how to do thisI cant find it anywhere in my book.
It's best to use standard form for large numbers, so f 3x10^15Hz (3 and 15 noughts)Work out energies in joulesThe photon energy, E hf 6.63x10^-34 x 3x10^15 1.99x10^-18 J The work function 4.1eV 4.1 x 1.6x10^-19 6.56x10^-19 J The photon energy is used to knock the electron out and any left over energy is given as KE to the electronThis gives Einstein's photoelectric equation: Photon energy (work function) + (KE of electron) KE (Photon energy) - (work function) 1.99x10^-18 - 6.56x10^-19 1.33x10^-18J This is the maximum KE of the electrons, as they can lose some of it on the way out, bumping into atomsSo max KE of electrons 1.33x10^-18J deBroglie wavelength is given by h/mv (mv is momentum, pmv), so we need electron's speed Since KE mv^2/2, v sqrt(2KE/m) sqrt (2x1.33x10^-18 / 9.11x10^-31)) 1.71 x 10^6m/s deBroglie wavelength h/mv 6.63x10^-34 / (9.11x10^-31 x 1.71x10^6) 4.3x10^-10m Multiply by 10^9 to change to nm, giving 0.43nm.
Pinhole cameras do not need a lens! Go down to the local camera store if there is one left somewhere! Get the photographic paperIt comes in a closed packageDo not open this in the light! I put up a red bulb in the bathroom, covered the crack under the door and turned on the red bulb to get the paper out to put in my box with the hole in itThen cover the hole with a piece of tape, like electricians tapeSeal the box well so no light can get in other than through the pin holeTake the camera out and set it in the sun so you have something to photograph Uncover your pin hole and let the camera set there for about 10 to 15 minutesCover your hole back up and return to the dark roomYou will need two glass dishes the size of your photo paper and the developing liquidLet the print sit and soak in the liquid for the specified time, I think it was about 30 minutes, then put it in the rinse bathHang to dryThen you have your camera, and a picture you took with it.
