It has been found that the magnitude of a persistent current in this solenoid in the superconducting state decreases by about one part in 109 per hour. If we describe this decay by the equation, I = Io exp(-Rt/L) then determine an upper limit for the coil resistance, and hence a lower limit for the conductivity in the superconducting state.

28. evolution

29. environment, survive, offspring  

explanation:

the aurora is formed when charged particles emitted from the sun during a solar flare penetrate the earth's magnetic shield and collide with atoms and molecules in our atmosphere. these collisions result in countless little bursts of light, called photons, which make up the aurora.

auroras are generated by charged solar particles hitting molecules in earth's atmosphere. this usually happens in high latitudes, because our planet’s magnetic field tends to funnel these particles toward the poles. that’s why it can be experienced in northern ohio.