# Get help with physics questions

Recent questions in Physics
Alissa Hutchinson 2022-05-15 Answered

### Wien's displacement law in frequency domain When I tried to derive the Wien's displacement law I used Planck's law for blackbody radiation:${I}_{\nu }=\frac{8\pi {\nu }^{2}}{{c}^{3}}\frac{h\nu }{{e}^{h\nu /{k}_{b}T}-1}$Asking for maximum:It follows that numerator has to be $0$ and looking for $\nu >0$$3\left({e}^{h\nu /{k}_{b}T}-1\right)-h\nu /{k}_{b}T\cdot {e}^{h\nu /{k}_{b}T}=0$Solving for $\gamma =h\nu /{k}_{b}T$:$3\left({e}^{\gamma }-1\right)-\gamma {e}^{\gamma }=0\to \gamma =2.824$Now I look at the wavelength domain:but from Wien's law $\lambda T=b$ I expect that $hc/\gamma {k}_{b}$ is equal to $b$ which is not:$\frac{hc}{\gamma {k}_{b}}=0.005099$, where $b=0.002897$Why the derivation from frequency domain does not correspond the maximum in wavelength domain?I tried to justify it with chain rule:$\frac{dI}{d\lambda }=\frac{dI}{d\nu }\frac{d\nu }{d\lambda }=\frac{c}{{\nu }^{2}}\frac{dI}{d\nu }$where I see that $c/{\nu }^{2}$ does not influence where $d{I}_{\lambda }/d\lambda$ is zero.

anniferathonniz8km 2022-05-15 Answered

### What is meant by the half-life of a radioactive isotope?

deformere692qr 2022-05-15 Answered

### What will be the wavelength of second line belonging to balmer series in hydrogen emission spectrum?

Edith Mayer 2022-05-15 Answered

### Why is radioactive decay measured in half-life instead of the full time?

Landon Mckinney 2022-05-15 Answered

### Uses of Wien's law of displacementWiens's displacement law says${\lambda }_{\text{max}}T=\text{a constant}$So if I have the ${\lambda }_{\text{max}}$, I can find the temperature of a star. But if I have the temperature, is there any point in calculating ${\lambda }_{\text{max}}$? What information does that give us of the star, besides temperature?

sembuang711q6 2022-05-15 Answered

### Do someone knows the units of the spectra provided here ? It seems obvious enough that it's said nowhere, but even Wikipedia and other sites are quite blurry on this point.So, is it power (W), radiance($\phantom{\rule{mediummathspace}{0ex}}\mathrm{W}/{\mathrm{m}}^{2}\mathrm{s}\mathrm{r}$), or something else ?

Brooklynn Hubbard 2022-05-15 Answered

### Birth of a star. Now in order for a star (or proto-star) to be born, there must be nuclear fusion that happens between hydrogen atoms. My question is what happens to the electrons? Sal never mentions them, only isotopes of hydrogen, and basically only focuses on the nucleus of the atom. Do the electrons even matter?

deformere692qr 2022-05-15 Answered

### Calculate the energy of the first 4 photons emitted in the balmer series of the hydrogen spectrum. The Balmer series corresponds to nf=2 and the first 4 photons are the lowest energy transitions from higher energy levels. These 4 photons all hvae a wavelength in the visible spectrum.

Cesar Mcguire 2022-05-15 Answered

### What is the half-life of Americium-242?

Lexi Chandler 2022-05-15 Answered

### What is the third line in the Balmer series (m=2)?

Daphne Fry 2022-05-15 Answered

### Lines in one spectral series can overlap lines in another. Use the Rydberg equation to see if the range of wavelengths in the n₁=1 series overlaps the range in the n₁=2 series.

Aedan Tyler 2022-05-15 Answered

### What are first order half life units?

Iyana Macdonald 2022-05-15 Answered

### From the figure find the shortest wavelength present in the Balmer series of hydrogen, If

othereyeshmt4l 2022-05-15 Answered

### Deeper underlying explanation for color-shift in Wien's Law?Suppose we have a blackbody object, maybe a star or a metal (although I understand neither of these are actually blackbody objects, to some extent my understanding is they can approximate one). According to Wien's Law, as temperature increases, peak wavelength will decrease, so the color we observe will "blueshift." Despite having reached Wien's Law in my research, my understanding is that this is in fact not an answer to why the blueshift occurs, but just a statement that the blueshift does occur.So, is there some deeper reason why blackbodies peak wavelength emitted decreases with temperature?

rockandriot0odjn 2022-05-15 Answered

### Nuclear Feedback Loop (Fusion and Fission)What are the main factors that prevent a feedback loop being created by using a hybrid method of fission and fusion. Fusion building up to fissionable materials, and fission breaking down till fusion is possible. Ex: numbers of neutrons, cross section for interaction, the gap between elements, amount of energy needed, probability of correct species being generated.Further, would it be possible to at least get a few occurrences of the fission/fusion cycle.

revistasbibxjm87 2022-05-15 Answered

### De Broglie wavelength of an electronIf an electron which already possesses some kinetic energy of $X\phantom{\rule{thinmathspace}{0ex}}\mathrm{e}\mathrm{V}$ is further accelerated through a potential difference of $X\prime \phantom{\rule{thinmathspace}{0ex}}\mathrm{V}$, then is it correct to state that the electron now has a total kinetic energy of $\left(X+X\prime \right)\phantom{\rule{thinmathspace}{0ex}}\mathrm{e}\mathrm{V}$? Using this information, am I allowed to substitute this value in the de Broglie equation to find the wavelength of the electron?

poklanima5lqp3 2022-05-15 Answered

### We have two particles $A$ and $B$ flying with different speed. Now the rest frame for $A$ and $B$ is not the same. But is the inertial frame the same? Or would be the inertial frame the same if we have a third fix point $C$ and we would observe them both from $C$?For me it seems logical to have $3$ frame of references. From the point of view of $A$, from the point of view of $B$ and from an independent point of view $C$. Is this correct?

Daphne Haney 2022-05-15 Answered

### What is a homogeneous and isotropic frame of reference?I have heard that inertial frames of reference in the context of special relativity are both isotropic and homogeneous. I know what isotropic and homogeneous mean in a general context, but what do they mean when relating to a frame of reference?

ga2t1a2dan1oj 2022-05-15 Answered

### How many kilograms of waters are needed to obtain the 198.8 mol of deuterium, assuming that deiterium is 0.01500% of natural hydrogen?

Lexi Chandler 2022-05-15 Answered