The microscope available in your biology lab has a converging lens (the eyepiece) with a focal length of 2.50 cm mounted on one end of a tube of adjustable length. at the other end is another converging lens (the objective) that has a focal length of 1.00 cm . when you place the sample to be examined at a distance of 1.30 cm from the objective, at what length l will you need to adjust the tube of the microscope in order to view the sample in focus with a completely relaxed eye

The dipole moment of the water molecule (h2o) is 6.17x10^-30 c.m. consider a water molecule located at the origin whose dipole moment p points in the +x-direction. a chlorine ion ( of charge-1.60x10^-19c , is located at x=3.00x10^-9m . assume that is much larger than the separation d between the charges in the dipole, so that the approximate expression for the electric field along the dipole axis can be used. a) find the magnitude of the electric force that the water molecule exerts on the chlorine ion. b) what is the direction of the electric force. -x-direction or +x-direction c) is this force attractive or repulsive?