in a compound microscope the image formed by the objective lens is at a distance of 3cm from the eye lens. if the final image is at 25cm from the eye lens, calculate the focal length of the eye lens.

What is the average speed of a car that travels 40mph for 1 hour and 60 mph in another hour will mark brainliest

Large electric fields in cell membranes cause ions to move through the cell wall. the field strength in a typical membrane is 1.0 x 10 7 n/c. what is the magnitude of the force on a calcium ion with charge +e? what is its acceleration? is it possible for a particle with the same charge as as calcium to have a different acceleration if placed at this location? what would change the acceleration: mass of the particle? diameter of the particle?

Asmall 12.00g plastic ball is suspended by a string in a uniform, horizontal electric field with a magnitude of 10^3 n/c. if the ball is in equilibrium when the string makes a 30 ° angle with the vertical, what is the net charge on the ball?