What two things must occur in order for a light ray to refract when it strikes the boundary of a different medium?
A. It must strike the boundary at 45 degrees, and its frequency must change.
B. It must strike the boundary at an angle, and its frequency must change.
C. It must strike the boundary at 45degrees, and its wavelength must change.
D. It must strike the boundary at an angle, and its speed must change

In which of the following would the particles move most rapidly? a. ice at -20 °c b. water at 20 °c c. steam at 110 °c d. boiling water e. ice at 0 °c

Suppose a comet has an orbital period of 309.1 years around the sun. what is it’s average distance from the sun?

Two conductors, a and b, are each in the shape of a tetrahedron. but of different sizes. they are charged in the following manner: 1. tetrahedron a is charged from an electrostatic generator to charge q. 2. tetrahedron a is briefly touched to tetrahedron b. 3. steps 1 and 2 are repeated until the charge on tetrahedron b reaches a maximum value. if the charge on tetrahedron b was q/4 after the first time it touched tetrahedron a. what is the final charge qbmax on tetrahedron b?