In our real life, we have to cross many kinds of roads or doors. There are many doors or paths between them, which are one-way. That is, they only have access but do not have the right to go out or just have the right to go out but do not have access. For example, if we go to a park, there is a way to get in and another way to get out. You can buy a ticket and enter through the entrance. Again there is a way out just to get out. However, a guard is needed at this gate or street to do these things. But yes, you can enter through the exit and enter through the exit. But for that, the security of the gate has to be broken. For that you need to be stronger.
Electronics also needs some such paths. Circuits need to have some space where only one-way power of electricity needs to be kept. For example, to generate electricity by turning a motor and storing it in a battery, electricity from the motor is allowed to flow to the battery but electricity from the battery is not allowed to go to the motor.
A guard is also placed in the circuit to perform these tasks in electronics. That is – diode. A diode is an electronics invention that allows only one-way flow of electricity. And he does this through forward and reverse biasing. Again, a ticket is required to gain access through the gate. Similarly, even if the diode has access, the voltage of the current passing through it has to exceed a certain limit. Which is 0.6 voltage for Silicon diode and 0.3 voltage for Germanium diode. If the current is less than the voltage of the current, the current cannot enter through the diode even though it has access. And we call this voltage as knee voltage. The current can pass any diode even though the diode is not allowed like the gate. But for that, Diode has to break down. And the voltage of the current passing for breaking must be much higher. Which we call Zener Voltage.
Transistors are easily one of the reasons for the revolution in electronics. But the idea of inventing this transistor comes from the diode. Maybe we would never have come so far in electronics without the invention of the diode.
BSc in EEE CUET