Find the radius rrigel of the star rigel, the bright blue star in the constellation orion that radiates energy at a rate of 2.7×1031w and has a surface temperature of 11,000 k. assume that the star is spherical. use σ=5.67×10−8w/m2⋅k4 for the stefan-boltzmann constant and express your answer numerically in meters to two significant figures.

Which atomic model was proposed as a result of j. j. thomson’s work?

Consider a uniformly charged ring in the xy plane, centered at the origin. the ring has radius a and positive charge qdistributed evenly along its circumference. a)what is the direction of the electric field at any point on the z axis? . b)what is the magnitude of the electric field along the positive z axis? use k in your answer, where k=14πϵ0. d)the ball will oscillate along the z axis between z=d and z=−d in simple harmonic motion. what will be the angular frequency ω of these oscillations? use the approximation d≪a to simplify your calculation; that is, assume that d2+a2≈a2. express your answer in terms of given charges, dimensions, and constants

Jenny wants to test the electrical conductivity of two substances dissolved in water. she is preparing the containers for the experiment. which factor is most important for her to control? a) volumes of the solutions b) appearance of the solutions c) temperatures of the solutions d) concentrations of the solutions