Yang Yang bought a new type of fully enclosed nickel-cadmium battery (similar in appearance to lead-acid battery). It can be seen from the nameplate that the power supply voltage of the battery is 6 volts, and the maximum can be. The specific scheme is as follows: the brief steps of the required equipment operation: the method of distinguishing the positive and negative poles of the battery: Method 1: ammeter, 1 0Ω fixed resistance,1switch, and several wires. In the series circuit composed of ammeter, fixed value resistor, switch and nickel-cadmium battery, close the switch and observe the deflection of ammeter pointer. If the ammeter pointer deviates forward, it is connected to the battery positive electrode of the ammeter positive electrode. Method 2: Voltmeter, several wires. Form a series circuit of voltmeter and nickel-cadmium battery? If the voltmeter deflects forward, the positive terminal of the voltmeter is connected with the positive terminal of the battery; ?

In reverse deflection, the negative electrode of the battery is connected with the positive electrode of the voltmeter; Method 3: Solenoid, switch, small magnetic needle, how many wires? A solenoid, a switch and a nickel-cadmium battery form a series circuit, and a small magnetic needle is placed at one end of the solenoid, as shown in the figure:

When the switch is closed and the small magnetic needle is stationary, as shown in the figure, according to the interaction law between magnetic poles, it is concluded that the right end of the energized solenoid is N pole, and then the current direction is determined by the right-hand spiral law. The right end of the power supply is the negative electrode of the battery and the left end is the positive electrode. Conversely, if the N pole of the small magnetic needle points to the left, the right end of the power supply is the positive electrode of the battery and the left end is the negative electrode.