An electric dipole lies on the x-axis containing a charge of
-2.5 nc at x = -10.0 cm, and a +2.5 nc charge at x =+10.0 cm. find the electric field 1 on the x-axis at the point (20.0 cm, 0) 2 on the y-axis at the point (0, 10.0 cm)
in the model of the hydrogen atom, the proton,(+e) and electron, (-e) (having charge =±e =±1.6x10^−19c) are separated by 5.29x10^-11m. calculate the electric potential energy of this atom.
suppose turbulent motions in thunderstorms cause charge separations that result in a potential difference of 50 mv between the cloud and the ground. when lightning occurs, it transfers 10 c of charge between the cloud and ground. how much energy is released in the lightning?

Search coils and credit cards. one practical way to measure magnetic field strength uses a small, closely wound coil called a search coil. the coil is initially held with its plane perpendicular to a magnetic field. the coil is then either quickly rotated a quarter-turn about a diameter or quickly pulled out of the field. (a) derive the equation relating the total charge q that flows through a search coil to the magnetic-field magnitude b. the search coil has n turns, each with area a, and the flux through the coil is decreased from its initial maximum value to zero in a time ∆t. the resistance of the coil is r, and the total charge is q = i∆t, where i is the average current induced by the change in flux. (b) in a credit card reader, the magnetic strip on the back of a credit card is rapidly “swiped” past a coil within the reader. explain, using the same ideas that underlie the operation of a search coil, how the reader can decode the information stored in the pattern of magnetization on the strip. (c) is it necessary that the credit card be “swiped” through the reader at exactly the right speed? why or why not?