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Rosario L.

Physics 103

32 minutes ago

Explain how earth is made up of material supernovae

Adine J.

Physics 103

5 hours ago

Two charged spheres are 8.45cm apart. They are moved, and the force on each of them is found to have been tripled. How far apart are they now?

Notreal N.

Physics 103

11 hours ago

When food is irradiated with gamma rays from a cobalt-60 source, does the food become radioactive? Defend your answer.

Patrick B.

Physics 103

11 hours ago

Elements above uranium in the periodic table do not exist in any appreciable amounts in nature because they have short half-lives. Yet there are several elements below uranium in atomic number with equally short half-lives that do exist in appreciable amounts in nature. How can you account for this?

Michelle J.

Physics 103

11 hours ago

At 6:00 am a hospital uses its cyclotron to make 1 milligram of the isotope fluorine-18 for use as a diagnostic tool with its PET scanner. The half-life of F-18 is 1.8 hours. How much F-18 is left at 3:00 pm? At midnight? Should the hospital plan to make more F-18 the next morning?

Patrick P.

Physics 103

11 hours ago

A carbon dioxide laser used in surgery emits infrared radiation with a wavelength of 10.6$\mu m .$ In $1.00 ms,$ this laser raised the temperature of 1.00 $cm^{3}$ of flesh to $100^{\circ} C$ and evaporated it. (a) How many photons were required? You may assume flesh has the same heat of vaporization as water. (b) What was the minimum power output during the flash?

Patrick P.

Physics 103

11 hours ago

What is the power in diopters of a camera lens that has a 50.0 mm focal length?

Lisa M.

Physics 103

11 hours ago

The brightest star in the sky is Sirius, the Dog Star. It is actually a binary system of two stars, the smaller one (Sirius B) being a white dwarf. Spectral analysis of Sirius B indicates that its surface temperature is 24,000 K and that it radiates energy at a total rate of 1.0 $\times$ 10$^{25}$ W. Assume that it behaves like an ideal blackbody. (a) What is the total radiated intensity of Sirius B? (b) What is the peak-intensity wavelength? Is this wavelength visible to humans? (c) What is the radius of Sirius B? Express your answer in kilometers and as a fraction of our sun's radius. (d) Which star radiates more $total$ energy per second, the hot Sirius B or the (relatively) cool sun with a surface temperature of 5800 K? To find out, calculate the ratio of the total power radiated by our sun to the power radiated by Sirius B.

Benjamin M.

Physics 103

11 hours ago

Light of a certain frequency has a wavelength of 526 nm in water. What is the wavelength of this light in benzene?

Christopher G.

Physics 103

11 hours ago

Light with a frequency of $5.80 \times 10^{14}$ Hz travels in a block of glass that has an index of refraction of 1.52. What is the wavelength of the light (a) in vacuum and (b) in the glass?

Adine J.

Physics 103

1 day, 5 hours ago

An electron moves with velocity v? =(6.6i?5.6j)×104m/s in a magnetic field B? =(?0.60i+0.70j)T. Part A Determine the x-component of the force on the electron.

Adine J.

Physics 103

1 day, 6 hours ago

What is the velocity of a beam of electrons that goes undeflected when passing through perpendicular electric and magnetic fields of magnitude 8400 V/m and 7.8×10?3 T , respectively?

Adine J.

Physics 103

1 day, 7 hours ago

A 46.0 cm -long solenoid 1.35 cm in diameter is to produce a field of 0.350 mT at its center. Part A How much current should the solenoid carry if it has 735 turns of wire?

Patrick S.

Physics 103

1 day, 10 hours ago

Show that when light reflects from two mirrors that meet each other at a right angle, the outgoing ray is parallel to the incoming ray, as illustrated in the following figure.

Patrick L.

Physics 103

1 day, 10 hours ago

A 2.50 -W beam of light of wavelength 124 nm falls on a metal surface. You observe that the maximum kinetic energy of the ejected electrons is 4.16 $\mathrm{cV}$ . Assume that each photon in the beam ejects a photoelectron. (a) What is the work function (in electron volts of this metal? (b) How many photoelectrons are ejected eachsecond from this metal? (c) If the power of the light beam, but not its wavelength, were reduced by half, what would be the answer to part (b)? (d) If the wavelength of the beam, but not its power, were reduced by half, what would be the answer to part (b)?

Janet R.

Physics 103

1 day, 10 hours ago

(II) A hydrogen atom is in the 5$d$ state. Determine ($a$) the principal quantum number, ($b$) the energy of the state, ($c$) the orbital angular momentum and its quantum number $\ell$ and (d) the possible values for the magnetic quantum number.

Patrick F.

Physics 103

1 day, 10 hours ago

A hydrogen atom in the 5$g$ state is placed in a magnetic field of 0.600 $T$ that is in the $z$-direction. (a) Into how many levels is this state split by the interaction of the atom's orbital magnetic dipole moment with the magnetic field? (b) What is the energy separation between adjacent levels? (c) What is the energy separation between the level of lowest energy and the level of highest energy?

Amanda B.

Physics 103

1 day, 10 hours ago

The energy-level scheme for the hypothetical oneelectron element Searsium is shown in $\textbf{Fig. E39.25}$. The potential energy is taken to be zero for an electron at an infinite distance from the nucleus. (a) How much energy (in electron volts) does it take to ionize an electron from the ground level? (b) An 18-eV photon is absorbed by a Searsium atom in its ground level. As the atom returns to its ground level, what possible energies can the emitted photons have? Assume that there can be transitions between all pairs of levels. (c) What will happen if a photon with an energy of 8 eV strikes a Searsium atom in its ground level? Why? (d) Photons emitted in the Searsium transitions $n$ = 3 $\rightarrow$ n = 2 and $n$ = 3 $\rightarrow$ n = 1 will eject photoelectrons from an unknown metal, but the photon emitted from the transition $n$ = 4 $\rightarrow$ n = 3 will not. What are the limits (maximum and minimum possible values) of the work function of the metal?

Julie M.

Physics 103

1 day, 10 hours ago

(a) What accelerating potential is needed to produce electrons of wavelength 5.00 nm? (b) What would be the energy of photons having the same wavelength as these electrons? (c) What would be the wavelength of photons having the same energy as the electrons in part (a)?

Vanessa M.

Physics 103

1 day, 10 hours ago

Red light with wavelength 700 nm is passed through a two-slit apparatus. At the same time, monochromatic visible light with another wavelength passes through the same apparatus. As a result, most of the pattern that appears on the screen is a mixture of two colors; however, the center of the third bright fringe ($m$ = 32) of the red light appears pure red, with none of the other color. What are the possible wavelengths of the second type of visible light? Do you need to know the slit spacing to answer this question? Why or why not?

Casey K.

Physics 103

1 day, 10 hours ago

What is the thinnest film of a coating with $n$ = 1.42 on glass ($n$ = 1.52) for which destructive interference of the red component (650 nm) of an incident white light beam in air can take place by reflection?

Diamond I.

Physics 103

1 day, 12 hours ago

The work function of cesium is 1.6 x 10-19 J. Calculate the maximum speed of the electrons emitted when yellow light is used (? = 0.589 ?m), in meters per second. Use three significant figures.

Diamond I.

Physics 103

1 day, 12 hours ago

Calculate the momentum of a photon of frequency 2.5 x 1015 Hz in kg m/s

Karam S.

Physics 103

2 days, 8 hours ago

Seismographs measure the arrival times of earthquakes with a precision of 0.100 s. To get the distance to the epicenter of the quake, they compare the arrival times of S- and P-waves, which travel at different speeds) If S- and P-waves travel at 4.00 and 7.20 km/s, If they arrive with a delay of 3s, how far is the epicenter of the earthquake?

Karam S.

Physics 103

2 days, 8 hours ago

This is College Physics Answers with Shaun Dychko. Two types of waves produced by an earthquake are transverse secondary waves which travel at 4.00 kilometers per second and longitudinal P waves which travel at 7.20 kilometers per second. The P waves get their name because they are primary or first; since they travel faster, they are the first ones that will be detected by a seismograph here whereas secondary waves travel slower and they are detected second. Now being able to measure the difference in the amount of time it takes for the waves to travel from the epicenter of the earthquake to the detector... that time difference will be used to measure the distance to the epicenter— which I guess is all the way here. Okay! So we can say that this distance is the speed of the secondary wave multiplied by the time it takes the secondary wave to reach the detector which we can't measure because we don't know when the earthquake begins so we can't figure out how much time it takes but we'll see that it doesn't matter in a second. This distance can also be written as the speed of the primary wave multiplied by the time it takes and we can rearrange each of these for their respective times so t S is d over v S and t P is d over v P. Now the thing that we can measure is the difference in the amount of time that each one takes so the difference between the secondary wave and the primary wave and that will be d over v S minus d over v P. and we can factor out the d and say that it's distance equals 1 over or distance time is 1 over v S minus 1 over v P. And in order to solve for d here which we wanna do since we wanna find out what is the uncertainty in distance based on knowing the uncertainty in this time difference measurement, we have to find a formula first for the distance. So we are gonna divide both sides by this bracket but that's gonna get messy so let's turn it into a single fraction and so we'll multiply top and bottom here by v P and multiply top and bottom here by v S and this works out to v P minus v S all over v Sv P so we have made a common denominator here between these two terms and written it as a single fraction and we have t S minus t P over here by the way. Now we multiply both sides by v Sv P over v P minus v S and that works out to d equals v Sv P times this time difference divided by v P minus v S. So the difference in the distance or the uncertainty in the distance measurement will be the uncertainty in the time difference measurement multiplied by all this same stuff and divided by this. So I mean I could have written a bit more detail here... you could say that the upper limit to the possible distance is v Sv P times t S minus t P upper divided by v P minus v S and then you know actual whatever distance that is this and then the difference in these distances d S minus d or d upper minus d is this whole thing minus this whole thing. Now you can factor out the v Sv P over v P minus v S from both of these terms and you end up with this expression here where we have t S minus t P upper limit minus t S minus t P. Okay! So we can plug in numbers at this point so we have the secondary wave speed multiplied by the primary wave speed multiplied by this uncertainty in our time difference measurement of 0.100 seconds divided by the difference in wave speeds and that is 0.900 kilometers. Now this uncertainty is small enough that it's possible to be certain which country conducted a nuclear test although changes in the wave propagation speed or uncertainty in that wave propagation speed will certainly add much more to our uncertainty in this distance.

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