What is the refractive index of a medium?

Certain bacteria (such as aquaspirillum magnetotacticum) tend to swim toward the earth’s geographic north pole because they contain tiny particles, called magnetosomes, that are sensitive to a magnetic field. if a transmission line carrying 100 a is laid underwater, at what range of distances would the magnetic field from this line be great enough to interfere with the migration of these bacteria? (assume that a field less than 5% of the earth’s field would have little effect on the bacteria. take the earth’s field to be 5.0 * 10-5 t, and ignore the effects of the seawater.)

Which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?

The reason a penny thrown straight up inside a bus will come back to your hand is that you,the bus,the air inside the bus, and the penny are all moving at the same velocity. true or false