Astudent places a large pot of cold water on a stove and heats it for one minute. then she takes the pot of water off the burner and places it on the counter. which best describes the convection currents?

a. convection currents move thermal energy from the stove to the pot, and then from the pot to the water.
b. after the stove is turned off, convection currents continue to transfer energy through the water for a period of time.
c. convection currents in the water cause warmer, denser water to rise and transfer energy upward.
d. when the stove is turned on, convection currents cause an increase in the chemical energy of water molecules.

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