Radioactive iodine (radioiodine) is given to patients with some forms of thyroid cancer in order to destroy the cancer cells. 131I has a half-life of 8 days. Women who have been treated with 131I are advised to not become pregnant for 180 days (approximately 6 months) to avoid the radioactive contamination of a developing fetus. If a woman has been given a dose of 10 mCi (millicurie, a measurement of radiation), how much 131I will still be in her system when she can safely become pregnant?

A. 1.7 x 10-6 mCi
B. 22.5 x 10-6 mCi
C. There will be no iodine-131 left in her system after 180 days.
D. 3.125% of the original isotope

the small 0.38-kg slider is known to move from position a to position b along the vertical-plane slot. determine (a) the work done on the body by its weight and (b) the work done on the body by the spring. the distance r = 0.70 m, the spring modulus k = 154 n/m, and the unstretched length of the spring is 0.53 m

explanation:

-reverse card

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.