A farsighted person wears glasses that enable them to read a book held at distance of 25.0cm from their eyes, even though their near point is 57.0cm. Their glasses are a distance 2.00cm from their eyes. What is the focal lengh of power of the lens?

Ametal ring 4.20 cm in diameter is placed between the north and south poles of large magnets with the plane of its area perpendicular to the magnetic field. these magnets produce an initial uniform field of 1.12 t between them but are gradually pulled apart, causing this field to remain uniform but decrease steadily at 0.240 t/s . (a) what is the magnitude of the electric field induced in the ring? (b) in which direction (clockwise or counterclockwise) does the current flow as viewed by someone on the south pole of the magnet?