19.2 Mechanism of Conduction of Electricity
19.2.1 Conduction of Electricity in Metals
1. A lot of free electrons are available in an electric conductor.
2. They move freely throughout the crystal lattice structure of the conductor but frequently interact with the lattices, as shown in Figure 19.3.
Figure 19.3
3. The direction of linear motion of an electron changes each time the electron interacts with the lattice, and it gets scattered. The change in direction is a random process because the electron does not experience any net external force acting on it. Hence, the electrons move randomly in the conductor. There is no net motion in a particular direction and so the net electric current is zero.
4. Suppose an electric field is applied to the conductor so that the field exists within the conductor. In this case, a freely moving electron experiences an electric force since it lies within an electric field.
5. It accelerates and its speed increases. Each time it interacts with the crystal lattice, it slows down and then accelerates again.
6. As it continues to undergo its zigzag motion due to its interaction with the lattices, it tends to drift towards a direction opposite to the direction of the field due to the action of the electric force, as shown in Figure 19.4(a).
Figure 19.4
7. In general, all conduction electrons tend to drift along a particular direction in the conductor. Consequently, a current is set up.
19.2.2 Conduction of Electricity in Semiconductors
Figure 19.4 Movement of electrons and holes in a semiconductor under an electric field, showing opposite drift directions.
1. At room temperature two types of conduction charge carriers are available within a semiconductor like germanium and silicon. They are the negatively charged electrons and the positively charged holes.
2. When an electric field is set up within the semiconductor, the conduction electrons drift in a direction opposite to the direction of the field. On the other hand, the holes drift in the same direction as the electric field, as shown in Figure 19.4.
3. The drifting of electrons produces a current Ie in the semiconductor while the drifting of holes produces a current Ih. The net current I flowing in the conductor is
$\boxed{I=I_e+I_h}$
Applications of Conduction of Electricity in Metals and Semiconductors
Conduction of electricity plays an essential role in modern technology. Metals and semiconductors are widely used due to their unique electrical properties. Below are the major applications of conduction of electricity in metals and semiconductors.
1. Electrical Wiring (Metals)
Metals such as copper and aluminum are widely used in electrical wiring due to their high conductivity, allowing efficient transmission of electric current in homes and industries.
2. Power Transmission Systems (Metals)
Electricity is transmitted over long distances using metal conductors, ensuring minimal energy loss and reliable power distribution.
3. Electronic Devices (Semiconductors)
Semiconductors like silicon are essential in electronic devices such as smartphones, computers, and televisions, where controlled conduction of electricity is required.
4. Transistors and Integrated Circuits (Semiconductors)
Semiconductors are used to manufacture transistors and integrated circuits, which are the building blocks of modern electronics.
5. Solar Cells (Semiconductors)
Semiconductors are used in solar panels to convert sunlight into electrical energy through the photovoltaic effect.
6. Diodes and Rectifiers (Semiconductors)
Semiconductors are used in diodes to control the direction of current flow, commonly used in rectifiers and power supplies.
7. Heating Devices (Metals)
Metals conduct electricity and produce heat, making them suitable for heating appliances such as electric irons, heaters, and kettles.
8. Sensors and Smart Devices (Semiconductors)
Semiconductors are used in sensors for temperature, light, and pressure detection in modern smart technologies.
Conclusion
Metals are mainly used for efficient current conduction, while semiconductors are essential for controlling and manipulating electric current in advanced electronic systems. Understanding their applications helps in developing modern electrical and electronic technologies.
Conclusion: Conduction of Electricity in Metals and Semiconductors
Conduction of electricity in metals and semiconductors plays a vital role in modern science and technology. In metals, electric current is mainly carried by free electrons, allowing efficient and continuous flow of charge. This makes metals highly suitable for applications such as electrical wiring and power transmission.
In contrast, semiconductors have a controlled conductivity that depends on factors such as temperature and impurities (doping). This unique property allows them to regulate and manipulate electric current, making them essential in electronic devices such as diodes, transistors, and integrated circuits.
Overall, metals are used for efficient conduction, while semiconductors are crucial for controlling electrical behavior. Understanding both materials provides a strong foundation for developing advanced electronic systems and technologies.
Frequently Asked Questions (FAQ) – Conduction of Electricity in Metals and Semiconductors
1. What is conduction of electricity in metals?
Conduction of electricity in metals occurs due to the movement of free electrons that carry electric charge through the material.
2. What is conduction of electricity in semiconductors?
In semiconductors, conduction occurs through both electrons and holes, and it can be controlled by temperature and doping.
3. What is the main difference between metals and semiconductors?
Metals have high conductivity due to many free electrons, while semiconductors have moderate conductivity that can be controlled.
4. What are charge carriers in metals?
The charge carriers in metals are free electrons.
5. What are charge carriers in semiconductors?
The charge carriers in semiconductors are electrons and holes.
6. Why are semiconductors important in electronics?
Semiconductors are important because they can control the flow of electric current, making them essential in devices like diodes and transistors.
7. How does temperature affect conduction in semiconductors?
Increasing temperature increases the conductivity of semiconductors by generating more charge carriers.
8. Where are metals used in electrical applications?
Metals are used in wiring, power transmission lines, and electrical components due to their high conductivity.
9. Where are semiconductors used in real life?
Semiconductors are used in electronic devices such as computers, smartphones, solar cells, and sensors.
10. What is doping in semiconductors?
Doping is the process of adding impurities to a semiconductor to increase its conductivity.
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