23. What is the magnitude of magnetic field at the center of the orbit due to the electron's motion? (A) (B) (C) (D)(E) none of the above.

8. Consider a cube of density ρ and horizontal cross-sectional area L² with vertical height L. The cube is floating in a liquid with density ρ_L. At equilibrium a fraction L₀/L of the cube is immersed in the liquid. Now let's push down the cube a little bit and release it. What is the period of the subsequent oscillation? (A) (B)(C)(D)(E) none of the above.