How Does Electricity Flow? Key Mechanisms and Real-Life Applications
All the substances that are made up of atoms having charged particles are known as electrons and protons. These charged particles have respectively one single negative and another positive charge. On the fundamental particles, electricity in all forms is a result of this charge. The conduction of electricity is defined as the movement of the charged particles in a well-organized manner by resulting in a net charge movement through the material. When the charged particles move in an orderly style, we get an electric current.
Conduction of Electricity
Electricity conduction can be applied for various substances like solids, liquids, and other compounds. Let us have a look on the conduction of electricity on a few compounds like liquids and substances.
Conduction of Electricity in Liquids
Metals can conduct electricity via mobile electrons. The outermost electrons in the metals are held loosely because of which they can move from one to another atom. That’s why metals are the excellent conductors of electricity. Besides, liquids conduct electricity by different means. Other than metals, the chemical bonding in liquids doesn’t allow for a free movement of electrons. This means before it can start conducting, we have to introduce charges into the water. Compounds such as ionic Compounds dissolve in water; they do so by breaking up or dissociating their bonds.
When the breakage of bond occurs, the components of these compounds break apart to yield multiple constituent atoms having a charge on the bond. The atom that loses single or multiple electrons has a number of protons rather than electrons, and likewise, an atom that gains electrons has a number of electrons to that of protons. This leads to an imbalanced charge leading to either a positive or a negative charge on the atom. The atom that becomes charged by gaining or losing one or more electrons is referred to as an Ion.
Conduction of Electricity in Substances
Let us look at an experimental setup to understand the flow of electricity via various liquids. We know that electricity is explained as the movement of charged particles through the body. In solids such as metals, the electrons are loosely bound to the atoms because of which electrons can freely move from atom to atom in a metal object. This electron mobility allows us to pass an electric current through it. If we can easily pass an electric current through objects, we call them Good electricity conductors. Materials that do not allow the electricity flow through it are known as insulators. The liquid elements that only conduct electricity are liquid metals, whereas Mercury is the only metal liquid at room temperature. This experiment helps us to identify how electricity is exactly conducted through a liquid.
Coming back to the experimental setup, this setup is used to test the electrical conduction in a substance. This also consists of an electric circuit connected to a glass lamp attached to a voltage source that is used to power this lamp like a battery. There is a discontinuity noticed in the circuit as an intentional break in it. This particular breakage is replaced with two electrodes that can be dipped into the substances to examine the electrical conduction nature through the body.
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When the electrodes are dipped into the conducting substance such as mercury, the current passes from the circuit, and then, from the electrode into the conducting material, and from there, it passes on to the other electrode, then to the bulb thereby completing the entire circuit. If the bulb glows, in turn, it is meant that the substance is conducting. Coming to a non-conducting substance, the current is unable to pass from the electrode to the substance, thereby breaking the circuit. In this case, the lamp stays off. This experiment is primarily conducted to check the conductivity of the solution. If the lamp lightens, it means the solution conducts electricity. If the lamp is dim, it means simply it conducts too little electricity. Let’s see this experiment results for various common solutions.
From the experiment taken, we deduce that there is something in salt that enables the electrical conduction in a solution. It means we must jump into what allows it to do so. The answer is simply Ions.
We also should consider that normal tap water has many compounds dissolved in it, which we treat as Hardness. The conductivity is largely based on this, and thus conductivity of tap water may vary from place to place. From this experiment, we also found which solutions conduct electricity and which do not.
FAQs on Conduction of Electricity in Physics: Complete Guide
1. What is meant by the conduction of electricity?
The conduction of electricity is the process by which electric charge moves through a substance. This movement is facilitated by charge carriers. In solid conductors like metals, the charge carriers are free electrons. In liquid conductors, such as electrolytic solutions, the charge carriers are ions (both positive and negative).
2. Why are metals good conductors of electricity?
Metals are excellent conductors because their atomic structure includes a 'sea' of delocalised or free electrons. These electrons are not tightly bound to any single atom and are free to move throughout the metallic lattice. When an external electric field (like from a battery) is applied, these free electrons experience a force and move in a specific direction, creating an electric current.
3. What is the main difference between electrical conductors, insulators, and semiconductors?
The primary difference lies in their ability to conduct electricity, which is determined by the availability of free charge carriers.
- Conductors: Have a large number of free electrons, offering very low resistance to current flow. Examples include copper and silver.
- Insulators: Have very few or no free electrons as they are tightly bound to atoms. They offer high resistance to current flow. Examples include rubber, glass, and wood.
- Semiconductors: Have electrical properties between those of conductors and insulators. Their conductivity can be significantly altered by temperature or by adding impurities (doping). Examples include silicon and germanium.
4. What are some key formulas used to describe the conduction of electricity?
Several fundamental formulas describe electrical conduction:
- Ohm's Law: V = IR, which relates voltage (V), current (I), and resistance (R).
- Electric Current: I = q/t, defining current as the rate of flow of charge (q) over time (t).
- Current and Drift Velocity: I = nAev_d, which links current to the number density of charge carriers (n), cross-sectional area (A), elementary charge (e), and drift velocity (v_d).
- Resistivity and Conductivity: ρ = R(A/L), where ρ is resistivity. Conductivity (σ) is its reciprocal, σ = 1/ρ.
5. How is electricity conducted differently in solids compared to liquids?
The mechanism of conduction varies based on the state of matter:
- In Solids (like metals): Conduction occurs exclusively through the movement of free electrons. The positive metal ions (kernels) remain fixed in their lattice positions.
- In Liquids (electrolytes): Conduction is due to the movement of mobile ions. When a voltage is applied, positive ions (cations) move towards the negative electrode (cathode), and negative ions (anions) move towards the positive electrode (anode).
6. Why is the direction of conventional current opposite to the flow of electrons?
This is a historical convention that predates the discovery of the electron. Early scientists, like Benjamin Franklin, assumed that electricity was a flow of positive charge. Therefore, the direction of current was defined as the direction a positive charge would move, i.e., from a high potential (positive terminal) to a low potential (negative terminal). Even after it was discovered that electrons (negative charges) are the actual charge carriers in metals, this established convention was retained for circuit analysis to avoid confusion.
7. How does the 'drift velocity' of electrons result in an electric current?
In a conductor without an electric field, free electrons move randomly at high speeds, but their net movement is zero. When an electric field is applied, the electrons are accelerated in the opposite direction of the field. However, they frequently collide with the lattice ions, which stops their acceleration. The result is a slow, average net velocity superimposed on their random motion, known as drift velocity. This slow, collective, and directional movement of billions of electrons constitutes the electric current we measure.
8. How does temperature affect the electrical conductivity of a material?
The effect of temperature on conductivity depends on the type of material:
- For Conductors (Metals): As temperature increases, the positive ions in the lattice vibrate more vigorously. This increases the frequency of collisions with the free electrons, impeding their flow. Consequently, the resistance increases and conductivity decreases.
- For Semiconductors: As temperature increases, more thermal energy is available to break covalent bonds, creating more free electrons and holes (charge carriers). This increase in carrier density is more significant than the effect of increased collisions, so the resistance decreases and conductivity increases.
9. What are some real-world applications of electrical conductors and insulators?
Both conductors and insulators are essential in our daily lives.
- Conductor Applications: Copper wires are used in household wiring and electronics for efficient current flow. Aluminium is used in long-distance overhead power lines because it is lightweight and conductive. Gold is used to plate connectors on high-end electronic devices due to its high conductivity and resistance to corrosion.
- Insulator Applications: Plastic and rubber coatings on electrical wires prevent short circuits and electric shocks. Ceramic discs are used on power poles to support high-voltage lines without letting electricity escape to the ground.
