Electricity is used daily to operate your cell phones, power transports, and keep your home appliances such as the refrigerator running. If you are attending physics tuition, you would know that the concept of electrical current is central to these operations. As current cannot normally be seen, it is often difficult to gain a perception of what it is. However, we can learn about it through its effects. Let’s learn about the current of electricity and its properties!
Everything we see is made up of tiny particles called atoms. Within these atoms, there are smaller particles called protons and electrons. Most electric charge is carried by the electrons and protons within an atom. Protons have a positive charge, while electrons have a negative charge.
An electric current is produced when electrons flow. It is defined as the rate of flow of charged particles moving through a particular cross-section of a conductor with respect to time. The SI unit of current is ampere (A), and it can be measured using an ammeter.
When two charged particles come into contact, the charge begins to flow from one conductor to another. In an electrical circuit, the potential difference between two points is the work needed per unit charge to move a charge from one point to another. The SI unit of potential difference is volts (V) and it can be measured by a voltmeter. The formula that describes this relationship is:
- V is the electric potential difference in volts
- W is the work done in joules
- Q is the charge in coulomb
Resistance and resistivity
One of the key differences between resistance and resistivity is that the resistance opposes the movement of free electrons, while resistivity is the property of the material that determines how well it resists or conducts electric current.
The resistance of a circuit component or device is directly proportional to the length of the conductor and temperature of the material, and inversely proportional to the cross-sectional area of the material. The SI unit of resistance is Ohms.
- l is the length of the conductor
- a is the cross section area of the conductor
- ρ is the resistivity of the material
Rearranging the formula, we can get a formula for resistivity. The SI unit of resistivity is Ohms-metre.
Electromotive force is the work done by the source to drive a unit charge round a complete circuit. Although both the electromotive force and potential difference are both measured in volts, they are not the same thing. Electromotive force is the conversion of other forms of energy to electrical energy which can be found by:
- e is the electromotive force
- E is the work done
- Q is the charge
Electric current is an essential and basic concept in electronic circuits. In our modern day, we have adapted electricity in our lives so much that it is difficult to imagine life without it. Thus, if you are aiming to pursue anything related to technology and electronics, it is important to know about electric current and its properties.
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