#114I don't understand the math of how they got the answer using the m=... equation. Especially where L=1/3.
#119I didn't understand the AAMC reasoning at all.
AAMC physics question pack #114 and #119

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Re: AAMC physics question pack #114 and #119
114: We know that we are trying to find the cavity mode number. Looking through the passage, the equation that would help us find that is mλm = 2L. We have L, the length of the laser cavity, which is 1/3m (this was given in the question). Although we don't have wavelength, the question gives us frequency and we can use the equation fm = c/λm, where c = 3 × 108 m/s, in order to find wavelength. From this, we get wavelength = 0.33 x 106m. Next, plug this back into the original formula in order to find m, which is the cavity mode number.
119: Be is undergoing electron capture here, where an electron is drawn into the nucleus and combines with a proton in order to create a neutron. Here, the mass number remains the same while the atomic number decreases by one. Therefore, the correct answer is Lithium with an atomic number of 3 and a mass number of 7.
119: Be is undergoing electron capture here, where an electron is drawn into the nucleus and combines with a proton in order to create a neutron. Here, the mass number remains the same while the atomic number decreases by one. Therefore, the correct answer is Lithium with an atomic number of 3 and a mass number of 7.