In daily life, we often have such experience. Put the dry battery that seems to be "dead" after being used in electric toys into the small alarm clock, and the pointer of the small alarm clock moves again. Why?
The dry battery can be equivalent to a combination of an ideal power supply and internal resistance. When using the battery, the electrical appliances (such as electric toys, alarm clocks, remote controls, etc.) and internal resistance are connected at both ends of the ideal power supply in series, so the sum of the internal resistance and the voltage on the electrical appliance is equal to the voltage of the ideal battery, that is, the voltage indicated in the battery (for example, the voltage of a commonly used No. 5 dry battery is 1.5 V), The voltage ratio of the two is equal to their resistance ratio.
The initial internal resistance of a new dry battery is generally very small and can be almost ignored. The resistance of the consumer is much greater than it, so almost all the voltage is distributed on the consumer. However, with the use of the battery, its internal substances have undergone complex electrochemical reactions, the internal resistance of the battery is increasing, the voltage distributed on the internal resistance is increasing, and the voltage on the external consumers is decreasing.
Electrical appliances such as electric toys have large power consumption, large current and small resistance. Therefore, with the increase of internal resistance of the battery, it can quickly approach or even exceed the resistance of electrical appliances such as electric toys, making the voltage of electrical appliances drop significantly. When the internal resistance of the battery rises to a certain value, the voltage of the electrical appliance is far less than the working voltage, so it can't work normally. We can see that the battery seems to be "dead" in the electric toy.
The small alarm clock and remote controller are low-power appliances with large resistance. It seems that the internal resistance of the battery without power is significantly less than that of the small alarm clock and remote controller, so the small alarm clock can still work normally at this time. Therefore, in terms of battery selection, alkaline zinc manganese batteries with small internal resistance and stable performance are generally used for electrical appliances requiring large working current, such as cameras, tape recorders and electric toys, and ordinary zinc manganese batteries are generally used for electrical appliances requiring small working current, such as remote controls, doorbells, clocks and watches.
The principle of waste battery reuse is so simple. As long as you use the basic physical knowledge, you will find many interesting and useful ways in life!