The energy and momentum of an electron are related to the frequency and wavelength of the associated matter wave by the relations:
$E=hv,p=\frac{h}{\lambda }$
But while the value of $\lambda$ is physically significant, the value of $v$ (and therefore, the value of the phase speed $v$ $\lambda$) has no physical significations. Why?

Q. A) Answer the following question: Quarks inside protons and neutrons are thought to carry fractional charges $[(+\frac{2}{3})e;(-\frac{1}{3})e]$.Why do they not show up in Millikan’s oil-drop experiment?

B) Answer the following question: What is so special about the combination $\frac{e}{m}$? Why do we not simply talk of 𝑒 and 𝑚 separately?

C) Answer the following question: Why should gases be insulators at ordinary pressures and start conducting at very low pressures?

D) Answer the following question: Every metal has a definite work function. Why do all photoelectrons not come out with the same energy if incident radiation is monochromatic? Why is there an energy distribution of photoelectrons?

E) Answer the following question: The energy and momentum of an electron are related to the frequency and wavelength of the associated matter wave by the relations:
$E=hv),(p=\frac{h}{\lambda })$
But while the value of $\lambda$ is physically significant, the value of v (and therefore, the value of the phase speed $v\lambda )$ has no physical significance. Why?

Q. Answer the following questions: (a) Quarks inside protons and neutrons are thought to carryfractional charges [(+2/3)e ; (–1/3)e]. Why do they not show upin Millikan’s oil-drop experiment? (b) What is so special about the combination e/m? Why do we notsimply talk of e and m separately? (c) Why should gases be insulators at ordinary pressures and startconducting at very low pressures? (d) Every metal has a definite work function. Why do allphotoelectrons not come out with the same energy if incidentradiation is monochromatic? Why is there an energy distributionof photoelectrons? (e) The energy and momentum of an electron are related to thefrequency and wavelength of the associated matter wave by therelations:E = h ν, p = λhBut while the value of λ is physically significant, the value of ν(and therefore, the value of the phase speed ν λ) has no physicalsignificance. Why?

Q. Wavelength $\left(\lambda \right)$, frequency $\left(\nu \right)$ and speed of sound wave $\left(v\right)$ are related by:

Q. The frequency, wavelength and speed of a sound wave are related as :