The following table lists the work functions of a few common metals, measured in electron volts. metal φ(ev) cesium 1.9 potassium 2.2 sodium 2.3 lithium 2.5 calcium 3.2 copper 4.5 silver 4.7 platinum 5.6 using these data, answer the following questions about the photoelectric effect. part a light with a wavelength of 190 nm is incident on a metal surface. the most energetic electrons emitted from the surface are measured to have 4.0 ev of kinetic energy. which of the metals in the table is the surface most likely to be made of? view available hint(s) submit part b of the eight metals listed in the table, how many will eject electrons when a green laser (λg=510nm) is shined on them? view available hint(s) submit part c light with some unknown wavelength is incident on a piece of copper. the most energetic electrons emitted from the copper have 2.7 ev of kinetic energy. if the copper is replaced with a piece of sodium, what will be the maximum possible kinetic energy k of the electrons emitted from this new surface? enter your answer numerically in electron volts to two significant figures. view available hint(s)

A. Lithium

The equation for the photoelectric effect is:

where

is the energy of the incident light, with h being the Planck constant, c being the speed of light, and being the wavelength

is the work function of the metal (the minimum energy needed to extract one photoelectron from the surface of the metal)

K is the maximum kinetic energy of the photoelectron

In this problem, we have

, so the energy of the incident light is

Converting in electronvolts,

Since the electrons are emitted from the surface with a maximum kinetic energy of

K = 4.0 eV

The work function of this metal is

So, the metal is Lithium.

B. cesium, potassium, sodium

The wavelength of green light is

So its energy is

Converting in electronvolts,

So, all the metals that have work function smaller than this value will be able to emit photoelectrons, so:

Cesium

Potassium

Sodium

C. 4.9 eV

In this case, we have

- Copper work function:

- Maximum kinetic energy of the emitted electrons: K = 2.7 eV

So, the energy of the incident light is

Then the copper is replaced with sodium, which has work function of

So, if the same light shine on sodium, then the maximum kinetic energy of the emitted electrons will be

your answer is, orbit around the nucleus