Small production: homemade traffic lights

Baby material: wood+battery box+electronic components+red, yellow and green LED lights

The little kit is so great! Now it is changed to mosaic type, and the corresponding round wooden stick can be inserted into the corresponding hole. Wood glue and other tools are not needed. It is more convenient to assemble.

Assembly tips:

The blue line on the diode is the positive pole of the LED lamp, and the red line is the negative pole. The voltage of red and yellow diodes actually only needs 1.8-2.2V, so a resistor is connected in series. The resistor limits the voltage, so the diodes will not burn out after a long time.

Learning knowledge: 1. Understand some basic traffic safety knowledge, and know the reason of stopping at red light and walking at green light.

2. Know that you should pay attention to your own safety when crossing the road.

Key points of the experiment: Understand that traffic lights are the application of parallel circuits. It is safe to stop at red light, walk at green light and walk at zebra crossing. Do you think of the traffic lights on the road whenever you hear this nursery rhyme? But do you know why the traffic lights are red and green? After studying this experiment, you may understand the mystery.

Experimental purpose: to understand the electronic components and their application to contact simple circuits

Experimental cognition: with whom the manufacturer of popular science equipment knows the traffic lights in reality, understand the traffic lights in small-scale science and technology production, and understand the role of each component: battery-providing energy; Light bulb-converts electric energy into light energy; Wires-connecting components and

Conducted current, that is, electricity flows regularly in a certain direction along the object that transmits electricity, which is invisible and intangible; Switch-control circuit; Battery box-place the battery.

A circuit through which current flows is called a circuit, also known as a conductive circuit. The simplest circuit is composed of power supply, load, wires, switches and other components. Circuit conduction is called a path. There is only a path through which current can pass in the circuit. A disconnection somewhere in a circuit is called an open circuit or an open circuit. If there is no load between the positive and negative poles of the power supply in the circuit, it is called short circuit, which is never allowed. Another kind of short circuit means that both ends of an element are directly connected, and the current flows through the directly connected part without passing through the element.

This condition is called short circuit of the element. Open circuit (or open circuit) is allowed, but the first short circuit is never allowed, because the short circuit of power supply will cause the power supply, electrical appliances and ammeter to burn out.