when a spherical mirror of focal length 20cm is inserted in water of refractive index 1.33 then the focal length of mirror becomes

Which of the following changes to a pipe would increase the conductance by a factor of 12? 1.quadrupling the length and tripling the radius.2.reducing the length by a factor of and doubling the radius.3.tripling the length and reducing the radius by a factor of .4.reducing the length but a factor of and doubling the radius.

When you turn on a battery-operated device, an electrical circuit is

Is there a point between a 10 nc charge and a 20 nc charge at which the electric field is zero?