4. A beam of electrons is accelerated through a potential difference of 9.0 kV before entering a velocity selector. If the B-field of the velocity selector is perpendicular to the velocity and has a value of 0.03 T, what value of the E-field is required (in the magnetic field region) if the particles are to be undeflected?

Apoint charge +q is at the origin. a spherical gaussian surface centered at the origin encloses +q. so does a cubical surface centered at the origin and with edges parallel to the axes. select "true" or "false" for each statement below. the electric flux through the spherical surface is greater than that through the cubical surface. suppose (for this statement only), that q is moved from the origin but is still within both the surfaces. the flux through both surfaces remains unchanged. the area vector and the e-field vector point in the same direction for all points on the spherical surface. the e-field at all points on the spherical surface is equal due to spherical symmetry. the flux through the spherical gaussian surface is independent of its radius.