How to determine the signs of the poles of a galvanic cell using a light bulb (or a resistor), a compass and a piece of wire?

How to determine the signs of the poles of a galvanic cell using a light bulb (or a resistor), a compass and a piece of wire? How do you know if a hacksaw blade (or an iron spoke) is magnetized without the help of tools and other bodies?

To determine the signs of a galvanic cell, it is necessary to make an electrical circuit from a galvanic cell, a piece of wire and a light bulb, then bring a compass to the section of the circuit, then in the direction of rotation of the arrow, using the bolt rule, determine the direction of the current, and then the signs of the poles To find out magnetized for a hacksaw blade it is necessary to find its center of gravity and hang it on the threads, if it is stably oriented in the meridional direction, then it is magnetized. The second option: break it in half and bring the ends to each other, if they interact, then the canvas is magnetized.

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