Raspberry Pi_Eng_25.4.1 Short and Resistance


Published Book on Amazon


All of IOT Starting with the Latest Raspberry Pi from Beginner to Advanced – Volume 1
All of IOT Starting with the Latest Raspberry Pi from Beginner to Advanced – Volume 2


출판된 한글판 도서


최신 라즈베리파이(Raspberry Pi)로 시작하는 사물인터넷(IOT)의 모든 것 – 초보에서 고급까지 (상)
최신 라즈베리파이(Raspberry Pi)로 시작하는 사물인터넷(IOT)의 모든 것 – 초보에서 고급까지 (하)


Original Book Contents


25.4   Basics of Electronic Circuit

 

Here, we will explain the basic knowledge of electronic circuit.

 

25.4.1  Short and Resistance

 

Short is also generally referred to as a short circuit, which means that two wires with different potentials are directly connected to each other, such as connecting a (+) wire and a (-) wire without a resistor in a circuit where electricity is supplied. When this direct connection is made, excessive current flows for a moment and spark occurs.


 

The current flowing in the circuit is calculated as I = V / R. Then, if a circuit is connected to a power source without using a separate resistor, there is only a specific resistance of the wire. In this case, if a voltage of 3V ~ 5V is connected in series, theoretically the current close to infinity will flow to the wire.

 

For example, assuming a voltage of 3V and a resistance of 0.001Ω, a large current of I = 3 / 0.001 = 3000A flows. If you use a small power source such as a battery, the battery will not be able to supply such current, so it will not cause a big problem. However, if you connect a power source that can supply high current, heat may be generated, resulting in electric wire burning or fire.

 

One way to prevent the circuit from this danger is to use a resistor of the appropriate size. The reason why the overcurrent flows is that the resistance is too low. Therefore, when a resistor of an appropriate size suitable for the voltage is used, the overcurrent does not occur originally. Another way to protect the circuit from overcurrent is to attach a fuse or circuit breaker to the circuit. The fuze is that if the current exceeds a certain level, the fuze dissolves and breaks, so that the power is cut off.