Sapling #25

[IreneSeo3F]

Hi! I'm having difficulty figuring out how to solve #25 on sapling.
#25) The E.coli bacterium is about 1.6 micrometers long. Suppose you want to study it using photons of that wavelength or electrons having that de Brogile wavelength. What is the energy Ephoton of the photon?
Which equation should I start with and how can I use the give information?

[Rachel Kho Disc 2G]

For energy of a photon, use E=hv and c=v(lambda). Then for the energy of an electron, use E=1/2mv^2. Don't forget to convert micrometers to meters because I absolutely made that mistake a couple of times! (1 micrometer=1*10^-6m).

[Brennan McGurrr 3C]

This question asks to solve for energy in two different ways. The first part asks for the energy of the photon, which moves at the speed of light. In this case you can use the formulas E=hv and c=(lambda)v. Combined its E=(hc)/(lambda). The second part asks for the energy that the electron gives off, which does not move at the speed of light. In this case you would use De Broglie's equation, lambda=h/(mv). v represents velocity in this equation not frequency. You would solve this equation for velocity and then use it in the equation for kinetic energy, E=(1/2)mv^2.

[Carolina Gomez 2G]

To solve for the energy of the photon, you want to use the equation E=hc/λ, which is derived from combining E=hv and c= λv. Then to solve for the energy of the electron, use the equation for kinetic energy, which is KE=1/2mv^2. First, you want to find the velocity of the electron by using the de Broglie equation λ=h/p. Since p=mv, you solve for v with λ=h/mv. Then use the velocity to solve for the energy using the kinetic energy formula.

[George Hernandez 3I]

For the photon, you would calculate the energy using e=hv. For the electron, use e=1/2mv^2. The reason why you use two different equations is because one involves mass while the other involves simply frequency. The photon's energy is calculated by converting it's frequency to the corresponding energy through planck's constant, while the electron's energy is calculated by multiplying half the mass (kg) by its velocity squared.