how can i get an electrical charge from a magnetic field.?
An electric field does not produce any electric charges; it moves already existing ones if they are mobile (like electrons in a conductor). A changing magnetic field will produce an electric field. You can produce a magnetic field that oscillates back and forth from up to down at 50 or 60 Hz using an electromagnet made from a coil of wire wrapped around an iron or steel rod. Another coil or loop of wire next to it will develop a voltage that also oscillates at that frequency. That’s how a transformer works. The two coil axes should be parallel for maximum voltage.
