Efficiency = (energy that does the job) / (total energy used)
= (45 J) / (120J)
I think you can handle the division.
Answer:

Explanation:
By Einstein's Equation of photoelectric effect we know that

here we know that
= energy of the photons incident on the metal
= minimum energy required to remove photons from metal
= kinetic energy of the electrons ejected out of the plate
now we know that it requires 351 nm wavelength of photons to just eject out the electrons
so we can say

here we know that

now we have

now by energy equation above when photon of 303 nm incident on the surface





You would get a wrong calculaton which if you are doing an experiment it can mess with the results
Car B, Car C, And Car E Are either speeding up or slowing down