Radioactivity and Nuclear Reactions

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Splitting one nucleus of U-235 releases about 30 million times more energy than when one molecule of dynamite explodes.

Slide 87

Nuclear Fusion

Splitting one nucleus of U-235 releases about 30 million times more energy than when one molecule of dynamite explodes.

In a nuclear fusion reaction, two small, light nuclei combine to form one larger, heavier nucleus.

Slide 88

Nuclear Fusion

Splitting one nucleus of U-235 releases about 30 million times more energy than when one molecule of dynamite explodes.

In a nuclear fusion reaction, two small, light nuclei combine to form one larger, heavier nucleus.

Fusion combines nuclei & fission splits them apart.

Slide 89

How are temperature & fusion related?

How can two nuclei get close enough to combine?

Slide 90

How are temperature & fusion related?

How can two nuclei get close enough to combine? They must be moving very fast.

Slide 91

How are temperature & fusion related?

How can two nuclei get close enough to combine? They must be moving very fast.

All nuclei positively charged

Thus repel each other

Slide 92

How are temperature & fusion related?

How can two nuclei get close enough to combine? They must be moving very fast.

All nuclei positively charged

Thus repel each other

KE must overcome electric force to push them close enough to combine

KE increases as temperature increases

Slide 93

How are temperature & fusion related?

How can two nuclei get close enough to combine? They must be moving very fast.

All nuclei positively charged

Thus repel each other

KE must overcome electric force to push them close enough to combine

KE increases as temperature increases

Temp must be millions of °C like Sun & other stars

Slide 94

How does the Sun produce energy?

The Sun, made mostly of H produces its energy by fusion of H nuclei

2 protons (H-1) fuse to make a H isotope (H-2); then H-1 + H-2 form an isotope of He-3.

Slide 95

How does the Sun produce energy?

To complete the process, 4 H nuclei combine into 1 He nucleus during which a small amount of matter changes into a huge amount of energy.