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riadik2000 [5.3K]
3 years ago
7

When on object’s spectral lines are shifted from their rest wavelengths to longer wavelengths, we say that the object’s spectrum

shows a redshift. When the lines are shifted to shorter wavelengths, we say that the object’s spectrum shows a blueshift. Which statement about an blueshift and a redshift is true?
Physics
1 answer:
neonofarm [45]3 years ago
4 0

Answer:

Both statements are true.

Explanation:

When a celestial object (stars, galaxies) is moving away from an observer its spectral lines¹ will be shifted to the red part of the spectrum² (longer wavelength), in the other hand if the celestial body is moving toward the observer, the spectral lines will be shifted to the blue part of the spectrum (shorter wavelength). That is known as the Doppler shift.

This Doppler shift can be explained with the Doppler Effect³, which is defined for the case of light as:    

\frac{\Delta \lambda}{\lambda_{0}} = \frac{v}{c}    (1)

Where \Delta \lambda is the wavelength shift, \lambda_{0} is the rest wavelength, v is the velocity of the source and c is the speed of light.

This redshift in distant galaxies is a strong evidence for the expansion of the universe. Equation 1 also allows the measurement of radial velocity from celestial objects.  

Summary:  

Blueshift:

\lambda

Redshift:

\lambda >\lambda_{0}

¹Spectral lines: Determines the presence of particular elements in the photosphere of an star.

²Spectrum: Decomposition of light in its characteristic colors (wavelengths).

³Doppler Effect: Change in the frequency of a wave as a consequence of the movement from a source relative to an observer or vice versa.

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Explanation:

1. Mass of the proton, m_p=1.67\times 10^{-27}\ kg

Wavelength, \lambda_p=4.23\times 10^{-12}\ m

We need to find the potential difference. The relationship between potential difference and wavelength is given by :

\lambda=\dfrac{h}{\sqrt{2m_pq_pV}}

V=\dfrac{h^2}{2q_pm_p\lambda^2}

V=\dfrac{(6.62\times 10^{-34})^2}{2\times 1.6\times 10^{-19}\times 1.67\times 10^{-27}\times (4.23\times 10^{-12})^2}

V = 45.83 volts

2. Mass of the electron, m_p=9.1\times 10^{-31}\ kg

Wavelength, \lambda_p=4.23\times 10^{-12}\ m

We need to find the potential difference. The relationship between potential difference and wavelength is given by :

\lambda=\dfrac{h}{\sqrt{2m_eq_eV}}

V=\dfrac{h^2}{2q_em_e\lambda^2}

V=\dfrac{(6.62\times 10^{-34})^2}{2\times 1.6\times 10^{-19}\times 9.1\times 10^{-31}\times (4.23\times 10^{-12})^2}

V=6.92\times 10^{34}\ V

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3 years ago
According to Wien's Law, how many times hotter is an object whose blackbody emission spectrum peaks in the blue, at a wave lengt
scZoUnD [109]

Answer:1.55 times

Explanation:

Given

First wavelength(\lambda _1)=450 nm

Second wavelength(\lambda _2)=700 nm

According wien's diplacement law

\lambda T=constant

where \lambda =wavelength

T=Temperature

Let T_1 and T_2 be the temperatures corresponding to \lambda _1 & \lambda _2 respectively.

\lambda _1\times T_1=\lambda _2\times T_2

\frac{T_1}{T_2}=\frac{\lambda _2}{\lambda _1}

\frac{T_1}{T_2}=\frac{700}{450}=1.55

Thus object with \lambda 450 nm is 1.55 times hotter than object with wavelength \lambda =700 nm

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A very long, uniformly charged cylinder has radius R and linear charge density λ. Find the cylinder's electric field strength ou
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The cylinder's electric field magnitude, at a distance <em>r</em> from the axis of the cylinder (greater than the cylinder's radius), is equal to E= \frac{\lambda}{2\pi \epsilon_0 \cdot r}

<h3>Further explanation</h3>

Matter is the building block of everything that we encounter in our lives. Matter is made of atoms, which are in turn made of tiny particles which are called electrons, protons, and neutrons. The ammount of these 3 elements, and their topological configuration in the atoms, is what determines what a certain element is (like Carbon, Hydrogen, Iron, etc).

In some cases, some elements may lose or gain some electrons. Regarded that this missing or extra electrons are not very high in number, the material doesn't lose any of its properties, however it will always try to get its number of electrons back to normal. This is when we say that an element has a <em>charge</em>, which is a measure of how much electrons a body needs to get back to normal. A body has positive charge if it lacks electrons, and has negative charge if it has extra electrons.

This charge causes the material to have an Electric field, which is a measure of how much does it attract or repel electrons. In the case of our problem, we need to compute exactly that, the Electric field. In our problem, we have an infinitely long cylinder with a linear charge density \lambda, this means that all parts of the cylinder have the same charge, and due to symmetry, the electric field is constant on the angular and longitudinal directions of the cylinder.

This makes easy to apply Gauss' Law, since for a Gaussian curve in the shape of a concentric cylinder (with a higher radius than that of our charged cylinder) we can write:

\Phi = \frac{\lambda \cdot L}{\epsilon_0}

Where \Phi is called the Electric flux. Since the electric field is constant for a given distance <em>r</em> from the axis of the cylinder we can write that:

\Phi = E \cdot 2\pi r \cdot L

Joining both our expressions we can get that:

E= \frac{\lambda}{2\pi \epsilon_0 \cdot r}

<h3 /><h3>Learn more</h3>
  • Description on Electric fields: brainly.com/question/8971780
  • Relation between electric fields and magnetism: brainly.com/question/2838625
  • How can we use electric charges: brainly.com/question/10427437
<h3>Keywords</h3>

Electrons, protons, electric field, cylinder, electric flux

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Answer:

F_{net} = 1.875\,N

Explanation:

Asúmase que la patinadora experimenta una aceleración constante. La fuerza neta experimentada por la patinadora:

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F_{net} = 1.875\,N

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