Solar Energy

By what process does the Sun generate energy?

• gradual expansion

• chemical reactions

• nuclear fission

• gravitational contraction

• nuclear fusion

At the center of the Sun, nuclear fusion converts hydrogen into

• hydrogen compounds such as methane.

• molecular hydrogen.

• radioactive elements such as uranium and plutonium.

• helium, gamma rays, and neutrinos.

• radiation and elements such as carbon and nitrogen.

Suppose you try to bring two protons close together. Because of the electromagnetic force, the two protons will

• collide.

• remain stationary.

• repel one another.

• join together to form a deuterium nucleus.

• attract one another.

According to modern science, approximately how old is the Sun?

• 25 million years

• 400 million years

• 10,000 years

• 4.5 billion years

What two physical processes balance each other to create the condition known as gravitational equilibrium in stars?

• gravitational force and surface tension

• the strong force and the electromagnetic force

• the strong force and the weak force

• gravitational force and outward gas pressure

Why do sunspots appear dark?

• They are regions nearly devoid of gas.

• They are composed of different elements than the rest of the sun.

• They are regions that do not emit any radiation.

• They are regions that are significantly cooler than the rest of the photosphere.

Energy balance in the Sun refers to a balance between _______.

• the amount of energy the Sun radiates into space and the amount of energy that reaches Earth

• the force of gravity pulling inward and the force due to pressure pushing outward

• the rate at which fusion generates energy in the Sun's core and the rate at which the Sun's surface radiates energy into space

• the mass that the Sun loses each second and the amount of mass converted into energy each second

The Sun's surface is called the _______.

• photosphere

• corona

• convection zone

• chromosphere

The Sun's average surface (photosphere) temperature is about _______.

• 1,000 K

• 37,000 K

• 5,800 K

• 1,000,000 K

What is the solar wind?

• the wind that causes huge arcs of gas to rise above the Sun's surface

• the uppermost layer of the Sun, lying just above the corona

• a stream of charged particles flowing outward from the surface of the Sun

• the strong wind that blows sunspots around on the surface of the Sun