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3 years ago

Which of the following statements about dark matter and dark energy is/are true?

Physics

1 answer:

REY [17]3 years ago

6 0

Answer:

A. Both exceed the matter-energy equivalent of luminous matter.

B. Dark matter has only an attractive gravitational effect, while dark energy is repulsive.

Explanation:

Dark matter and dark energy together constitute about ninety-five percent of the of total matter-energy equivalence in the universe. So, they exceed the matter-energy equivalent of luminous matter.

Dark energy is the repulsive force that is accelerating the expansion of the universe. Dark matter only has an attractive gravitational effect but does not interact with light of any kind.

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A beam of light traveling in air strikes a glass slab at an angle of incidence less than 90°. After entering the glass slab, wha

omeli [17]

Answer:

It gets refracted.

Explanation:

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3 years ago

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4 years ago

A 3.0 kg pendulum swings from point A of height ya = 0.04 m to point B of height yb = 0.12 m, as seen in the diagram below.

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3 years ago

Read 2 more answers

Calculate the Fermi energy and the conductivity at room temperature for germanium containing 5×10^16 arsenic atoms per cubic cen

Cloud [144]

Answer:

The Fermi energy is 0.568 eV and the conductivity at room temperature is 31.24 (Ωcm)⁻¹

Explanation:

Data given:

Nd = doping concentration = 5x10⁶/cm³

According the mass action law, the hole concentration is:

$P_{0} =\frac{n_{i}^{2} }{n_{0} } ,n_{i}=2x10^{13} /cm^{3}$

$E_{f} =E_{i} +KTln(\frac{n_{D} }{n_{i} } ),K=8.61x10^{-19} ,KT=0.026eV$

$E_{i} =\frac{E_{0} }{2} =\frac{0.63}{2} =0.315eV\\E_{f}=0.315+0.203=0.568eV$

The conductivity of n-type of semi-conductor is equal to:

The mobility of Germanium is 3900 cm²/Vs

σ = 1.6x10⁻¹⁹ * 5x10¹⁶ * 3900 = 31.24 (Ωcm)⁻¹

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3 years ago

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Answer:

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