An energy of 13.6 eV is needed to ionize an electron from the ground state of a hydrogen atom. Selecting the longest wavelength that will work from the those given below, what wavelength is needed if a photon accomplishes this task?
a. 60 nm
b. 80 nm
c. 70 nm
d. 90 nm
e. 40 nm
Question 2
Carla and Jenny are arguing about whether or not it is possible to escape the gravitational field of the Earth. Carla shows Jenny a system where mass m is rE (not the Earth's radius) distant from Earth and rP (not planet P's radius) distant from planet P, the mass being on the line connecting the Earth and planet P. Carla states that the mass m has escaped if FP on m = -FE on m. Jenny disagrees. Which one, if either, is correct, and why?
a. Carla, because the total gravitational force on m is zero at that point.
b. Carla, because there is no gravitational force from Earth on m at that point.
c. Carla, because there is no gravitational force on m from Earth when r > rE.
d. Jenny, because there is a gravitational force on m from Earth no matter how great the distance from the Earth.
e. Jenny, because the gravitational force from the Earth can only be blocked by a body that is larger than the Earth.
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