Watch dials are often painted with a compound containing tritium, which has a half-life of 12.3 years. when the tritium atom undergoes beta decay the emitted electron strikes a fluorescent pigment, which then glows. if your tritium-dial watch is giving off a certain amount of light, how many half-lives must pass until the watch gives off only one-eighth as much light?

3 half-lives

Explanation:

The decay rate of the watch light intensity is given by:

where : is the intensity of light that changes with time, : is the initial intensity of light, λ: is the decay constant and t: is the decay time

For light to be only one-eighth as much light, it means:

(1)

The half-life of the tritium decay is:

(2)

By entering equation (2) into equation (1), we can find the time that must pass until the watch gives off only one-eighth as much light:

Which correspond to the next half-lives:

So, until the watch gives off only one-eighth as much light must pass 3 half-lives.

I hope it helps you!

answer: d. a cme increases the amount of energy in the solar wind

explanation:

coronal mass ejections, also called cmes, are large clouds of plasma and magnetic field that erupt from the sun. only when the cloud is aimed at earth will the cme hit earth and therefore cause impacts. high-speed solar wind streams come from areas on the sun known as coronal holes.

get the total number of pieces of fruit and divide it by 4 to get the average. the result is the answer to the problem. 14 total number of fruits and there are 4 members. 14 divided by 4 is equals to 3.5.