Which of these is the best method to measure the distance to a star?

calculate the variations in the position of the star due to movement of earth in its orbit
measure the red shift of emitted light and use it in calculations
use doppler effect to calculate the shift in light traveling from star to earth in summer
use doppler effect to calculate the shift in light traveling from star to earth in winter

Which subatomic particle has a negative charge

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?

Aspecified volume of space contains an electric field for which the magnitude is given by e=e0cos(ωt). suppose that e0 = 20 v/m and ω = 1.0 × 107 s−1. part a what is the maximum displacement current through a 0.80 m2 cross-sectional area of this volume? express your answer with the appropriate units. idisp, max i d i s p , m a x = nothing nothing request answer part b how would this area have to be oriented relative to the electric field to get this maximum displacement current?