A loss or gain of electrons on a surface is __________ electricity? Please help
2 answers:
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The atom must lose 2 electrons
Explanation:
An atom consists of three types of particles:
- Protons, in the nucleus, with positive electric charge
- Neutrons, in the nucleus, with no electric charge
- Electrons, orbiting around the nucleus, with negative electric charge
As a result, the net electric charge of an atom is given by the number of protons minus the number of electrons:
Q = #p - #e
For a neutral atom, the number of protons and electrons is the same, so the net charge is zero.
In order for an atom to have a positive charge of +2, it means that there must be 2 protons more than the number of electrons. Since atoms exchange electrons (and not protons), this means that the atom must have "lost" 2 electrons.
In this problem, we have an atom with 13 protons: this means that initially it also has 13 electrons. However, later the atom lost 2 electrons, and as a result, the final charge is +2e.
Learn more about atoms:
#LearnwithBrainly
1) In the first case, the correct answer is
<span>A.Wavelengths measured would match the actual wavelengths emitted.
In fact, the stars are not moving relative to Earth, so there is no shift in the measured wavelength.
2) In this second case, the correct answer is
</span><span>A.Wavelengths measured would be shorter than the actual wavelengths emitted.
</span>in fact, since the stars in this case are moving towards the Earth, then apparent frequency of their emitted light will be larger than the actual frequency, because of the Doppler effect, according to the formula:
where f0 is the actual frequency, f' the apparent frequency, c the speed of light and vs the velocity of the source (the stars) relative to the obsever (Earth). Vs is negative when the source is moving towards the observer, so the apparent frequency f' is larger than the actual frequency f0. But the wavelength is inversely proportional to the frequency, so the apparent wavelength will be shorter than the actual wavelength.
<span>A.Wavelengths measured would match the actual wavelengths emitted.
In fact, the stars are not moving relative to Earth, so there is no shift in the measured wavelength.
2) In this second case, the correct answer is
</span><span>A.Wavelengths measured would be shorter than the actual wavelengths emitted.
</span>in fact, since the stars in this case are moving towards the Earth, then apparent frequency of their emitted light will be larger than the actual frequency, because of the Doppler effect, according to the formula:
where f0 is the actual frequency, f' the apparent frequency, c the speed of light and vs the velocity of the source (the stars) relative to the obsever (Earth). Vs is negative when the source is moving towards the observer, so the apparent frequency f' is larger than the actual frequency f0. But the wavelength is inversely proportional to the frequency, so the apparent wavelength will be shorter than the actual wavelength.