1) You have 16 kg of a radioactive sample with a certain half-life of 30 years.

Question

1) You have 16 kg of a radioactive sample with a certain half-life of 30 years. How much is left after 90 years?

a) 8kg

b) 4kg

c) 2kg

d) 1kg

2) you have two samples, A (T1/2 = 10 years) and B (T1/2 = 20 years), with initially different amounts. The initial amount of sample A is 64 kg, while the amount of sample B is unknown. If you observe theat the two amounts are equal after 40 years, what is the intial amount of B?

a) 32kg

b) 16kg

c) 8kg

d)4kg

3) sunlight is reflected from the surface of a calm Rappahannock River

a) is unpolarized

b) is at least partially polarized with its polarization parallel to the surface

c) is at least partially polarized with its polarization perpendicular to the surface

d) has undergone refraction by the surface of the river

4) a monochromatic laser beam enters a medium with higher index of refraction from a medium with lower index of refraction. How is the refracted angle compared to the incident angle?

a) larger

b) smaller

c) same

Explanation / Answer

b) 4kg

b) 16kg

b) is at least partially polarized with its polarization parallel to the surface

b) smallerÂ

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