Question 1

Thermonuclear fusion reactions in the core of the Sun convert four hydrogen nuclei into one helium nucleus. The helium nucleus has:

Accepted Answer

The helium nucleus has less mass than the sum of the four hydrogen nuclei. The mass difference is converted into energy according to the equation E = mc^2, as described by Albert Einstein's theory of relativity. This process powers the Sun.

Question 2

By how much does the mass of the Sun decrease each second because of the energy it radiates (its luminosity)?

Accepted Answer

A

Question 3

If the Sun were the same temperature but twice its present diameter, the amount of energy we would receive would:

Accepted Answer

The amount of energy we receive from the Sun is proportional to its surface area. If the Sun's diameter doubles, its surface area increases by a factor of four (since area is proportional to the square of the diameter), thus the energy we receive would increase by a factor of four.

Question 4

If the temperature of the surface of the Sun doubled, the amount of energy we would receive would:

Accepted Answer

The amount of energy radiated by a body (like the Sun) per unit area is proportional to the fourth power of its absolute temperature, according to the Stefan-Boltzmann law. Therefore, if the temperature doubles, the energy radiated increases by $2^4 = 16$ times.

Question 5

How much hydrogen is converted into helium and energy in the Sun each second?

Accepted Answer

The Sun converts approximately 600 million tons of hydrogen into helium and energy every second through the process of nuclear fusion in its core.

Question 6

The contraction of a star (or other object) due to its own gravity generates heat. If this process, known as the Kelvin-Helmholtz contraction, were to be the source of heat energy from the Sun, then the Sun's age:

Accepted Answer

The Kelvin-Helmholtz mechanism, if it were the sole source of the Sun's energy, would imply that the Sun could have been shining for about 25 million years. This is based on calculations of the gravitational potential energy available and the rate at which energy is radiated.

Question 7

The Sun emits light:

Accepted Answer

The Sun emits most of its light in the visible spectrum, making it the most intense. This is why the Sun appears yellow to our eyes. While the Sun does emit light at various wavelengths across the electromagnetic spectrum, the visible spectrum is the most intense.

Question 8

A positron is:

Accepted Answer

A positron is an antiparticle of an electron, which means it has the same mass as an electron but with a positive charge instead of a negative charge. It is not a proton (B), charged neutron (C), or a positively charged neutrino (D).

Question 9

How much matter is converted into energy in the Sun each second?

Accepted Answer

The answer of How much matter is converted into energy...

Question 10

If the Sun were much less massive, how would the pressure at the center compare to its present value?

Accepted Answer

The pressure at the center of the Sun is a result of the gravitational force acting on the mass of the Sun. If the Sun were much less massive, the gravitational force would be weaker, leading to a decrease in the pressure at the center.

Question 11

What is the dominant mechanism by which energy is transported through the core of the Sun?

Accepted Answer

The dominant mechanism by which energy is transported through the core of the Sun is radiative transport of energy, where energy is transported by photons. This is because the core of the Sun is extremely hot and dense, which makes it opaque to most forms of radiation. Photons that are produced by nuclear fusion reactions in the core of the Sun travel a very short distance before colliding with other particles, which causes them to change direction. As a result, photons are slowly diffused outward through the material in the core, carrying energy with them.

Question 12

Represented as a fraction of the solar radius, convection currents in the Sun's interior occupy what fraction of the Sun?

Accepted Answer

Convection currents in the Sun's interior occupy the outer 29% of the solar radius.

Question 13

The temperature at the center of the Sun, where thermonuclear processes take place, is approximately:

Accepted Answer

The temperature at the center of the Sun, where thermonuclear processes occur, is approximately 15 million Kelvin (1.5 × 10^7 K). This extreme temperature is necessary for the fusion of hydrogen into helium, the process that powers the Sun.

Question 14

According to the theoretical model of the Sun tabulated in Table 16-2 and shown graphically in Figure 16-3 of Universe, 11th ed., within what radial distance of the solar center is the vast majority of solar energy generated?
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Accepted Answer

The answer of According to the theoretical model of the...

Question 15

Virtually all of the Sun's mass is concentrated within what fraction of its radius?

Accepted Answer

The answer of Virtually all of the Sun's mass is...

Question 16

The density of the Sun decreases as you move outward from the core. Approximately where is the Sun's density equal to the density of water?

Accepted Answer

The answer of The density of the Sun decreases as...

Question 17

What is the nature and extent of the oscillations and waves in the Sun?

Accepted Answer

The Sun exhibits many millions of different oscillation modes or frequencies, akin to a complex musical instrument with a vast array of tones. These are not limited to a single or a few frequencies but span a wide range, each providing insights into different aspects of solar physics.

Question 18

How do the low-frequency sound waves associated with the 5-minute oscillations traverse the interior of the Sun?

Accepted Answer

Low-frequency sound waves associated with 5-minute oscillations are known as p-modes or pressure modes. These sound waves travel through the interior of the Sun by following curved paths due to the variation in the solar density, temperature, and pressure. When they reach the underside of the solar surface, they are partially reflected and partially transmitted. The transmitted waves interfere with the incoming waves, resulting in standing waves that cause the Sun's surface to oscillate. Therefore, option C is the correct answer.

Question 19

Solar sound waves:

Accepted Answer

Solar sound waves are indeed reflected back and forth between the solar surface and the deeper layers of the solar interior, a process that is crucial for the field of helioseismology, which studies the interior of the Sun by analyzing these waves.

Question 20

Sound waves on the Sun:

Accepted Answer

Sound waves on the Sun, also known as solar oscillations or helioseismology, can actually travel both inward and outward. These waves are generated by the turbulent motion of gases in the Sun's interior and can provide scientists with valuable information about the structure and dynamics of the solar interior. While the high temperature of the Sun may affect the propagation of sound waves, it does not prevent their existence. Sound waves can also travel through the entire volume of the Sun, not just along the outer surface or outward from the core.

Quiz 16: Our Star, the Sun

Thermonuclear fusion reactions in the core of the Sun convert four hydrogen nuclei into one helium nucleus. The helium nucleus has:

By how much does the mass of the Sun decrease each second because of the energy it radiates (its luminosity) ?

If the Sun were the same temperature but twice its present diameter, the amount of energy we would receive would:

If the temperature of the surface of the Sun doubled, the amount of energy we would receive would:

How much hydrogen is converted into helium and energy in the Sun each second?

The contraction of a star (or other object) due to its own gravity generates heat. If this process, known as the Kelvin-Helmholtz contraction, were to be the source of heat energy from the Sun, then the Sun's age:

The Sun emits light:

A positron is:

How much matter is converted into energy in the Sun each second?

If the Sun were much less massive, how would the pressure at the center compare to its present value?

What is the dominant mechanism by which energy is transported through the core of the Sun?

Represented as a fraction of the solar radius, convection currents in the Sun's interior occupy what fraction of the Sun?

The temperature at the center of the Sun, where thermonuclear processes take place, is approximately:

According to the theoretical model of the Sun tabulated in Table 16-2 and shown graphically in Figure 16-3 of Universe, 11th ed., within what radial distance of the solar center is the vast majority of solar energy generated?

Virtually all of the Sun's mass is concentrated within what fraction of its radius?

The density of the Sun decreases as you move outward from the core. Approximately where is the Sun's density equal to the density of water?

What is the nature and extent of the oscillations and waves in the Sun?

How do the low-frequency sound waves associated with the 5-minute oscillations traverse the interior of the Sun?

Solar sound waves:

Sound waves on the Sun:

Quiz 16: Our Star, the Sun

Thermonuclear fusion reactions in the core of the Sun convert four hydrogen nuclei into one helium nucleus. The helium nucleus has:

By how much does the mass of the Sun decrease each second because of the energy it radiates (its luminosity) ?

If the Sun were the same temperature but twice its present diameter, the amount of energy we would receive would:

If the temperature of the surface of the Sun doubled, the amount of energy we would receive would:

How much hydrogen is converted into helium and energy in the Sun each second?

The contraction of a star (or other object) due to its own gravity generates heat. If this process, known as the Kelvin-Helmholtz contraction, were to be the source of heat energy from the Sun, then the Sun's age:

The Sun emits light:

A positron is:

How much matter is converted into energy in the Sun each second?

If the Sun were much less massive, how would the pressure at the center compare to its present value?

What is the dominant mechanism by which energy is transported through the core of the Sun?

Represented as a fraction of the solar radius, convection currents in the Sun's interior occupy what fraction of the Sun?

The temperature at the center of the Sun, where thermonuclear processes take place, is approximately:

According to the theoretical model of the Sun tabulated in Table 16-2 and shown graphically in Figure 16-3 of Universe, 11th ed., within what radial distance of the solar center is the vast majority of solar energy generated? ​ ​

Virtually all of the Sun's mass is concentrated within what fraction of its radius?

The density of the Sun decreases as you move outward from the core. Approximately where is the Sun's density equal to the density of water?

What is the nature and extent of the oscillations and waves in the Sun?

How do the low-frequency sound waves associated with the 5-minute oscillations traverse the interior of the Sun?

Solar sound waves:

Sound waves on the Sun:

According to the theoretical model of the Sun tabulated in Table 16-2 and shown graphically in Figure 16-3 of Universe, 11th ed., within what radial distance of the solar center is the vast majority of solar energy generated?