B. an unstable arrangement of electrons
C. more than eight electrons in their valence shell
D. fewer than eight electrons in their valence shell
B. giant, main sequence star, white dwarf, neutron star
C. white dwarf, neutron star, giant, main sequence star
D. neutron star, white dwarf, main sequence star, giant
The following lists ofstars in order from least density to greatest density are giant, main sequencestar, white dwarf, neutron star. The answer is letter B. Aside from neutronstar being the densest star, it is also the smallest star compared to the giantstar, as its name implied.
Answer:
B
Explanation:
as a medium star
B. Superconducting
C. Contact
D. Permanent
Answer:
C) Contact
Explanation:
The magnet requires almost direct contact with the fridge to start its magnetic properties.
Answer:
Correct Answer is option D (permanent)
Explanation:
Permanent magnet
Permanent magnet is a magnet in which magnetic properties are present even in the absence of an external magnetic field. It has its own magnetic field.
Permanent type of magnetism is present in a magnet that we use to place a photograph on the refrigerator.This permanent magnet is made up of powdered ferrite and liquid plastic. The mixture of ferrite and plastic is heated at a particular temperature and then this heated mixture is placed in a strong magnetic field. Due to this applied magnetic field this mixture is turned into a permanent magnet.
By this method of it requires less material to create a permanent magnet.
I hope this answer will help you.
photon?
(1) 1.86 × 10^22 J (3) 4.14 × 10^−19 J
(2) 1.44 × 10^2 J (4) 3.18 × 10^−26 J
Taking into account the definition of photon, energy of a photon, wavelength, frecuency and propagation speed, the correct answer is the option (3): The energy of a photon with aa wavelength of 4.80×10⁻⁷ meter is 4.14×10⁻¹⁹ J.
You have to know that electromagnetic radiation carries energy, which can be absorbed or emitted. To explain the processes of emission and absorption, Plank and Einstein proposed that the energy of radiation is composed of indivisible units (quanta). In each elemental process only a quantum of light can be emitted or absorbed. Each of these quanta was called a "photon".
The exchanges of energy between matter and radiation take place not continuously, but by discrete and indivisible quantities or quanta of energy. The quantum of energy is proportional to the frequency of radiation.
The relationship between the amount of energy (E) transported by the photon and its frequency (f) is determined by the following expression, where the energy of a photon is obtained by multiplying Planck's constant h by the frequency f of electromagnetic radiation:
E=h×f
Wavelength is the minimum distance between two successive points on the wave that are in the same state of vibration. It is expressed in units of length (m).
On the other side, frequency is the number of vibrations that occur in a unit of time. Its unit is s⁻¹ or hertz (Hz).
Finally, the propagation speed is the speed with which the wave propagates in the medium, that is, it is the magnitude that measures the speed at which the wave disturbance propagates along its displacement.
The propagation speed relate the wavelength (λ) and the frequency (f) inversely proportional using the following equation:
v = f×λ
All electromagnetic waves propagate in a vacuum at a constant speed of 3×10⁸ m/s, the speed of light.
In this case, you know:
Replacing in the definition of energy of a photon:
E=h× (v÷λ)
E= 6.63×10⁻³⁴ Js× (3×10⁸ m/s ÷4.80×10⁻⁷ m)
Solving:
E= 4.14×10⁻¹⁹ J
Finally, the correct answer is the option (3): The energy of a photon with aa wavelength of 4.80×10⁻⁷ meter is 4.14×10⁻¹⁹ J.
Learn more about
definition of photon and energy of a photon:
wavelength, frecuency and propagation speed:
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b. the average kinetic energy of molecules
c. the average potential energy of molecules
d. the direction of the moving molecules in a substance
Temperature measures the average kinetic energy of molecules in a substance.
The correct answer is b. the average kinetic energy of molecules.
Temperature measures the average kinetic energy of molecules in a substance. When the temperature of a substance increases, the molecules move faster and have more kinetic energy. This is why substances generally expand when heated and contract when cooled.
For example, when you heat water, the temperature increases, and the water molecules move faster, eventually reaching a boiling point where they have enough kinetic energy to break the bonds and escape as steam.
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