What is electric charge? Electric charge is a fundamental physical property of matter. Electric charge can be positive or negative. Matter repels other matter of the same charge and attracts other matter having the opposite charge. The unit used for electric charge is a Coulomb [C]. While the exact nature of charge is still unknown at a fundamental level, it is generally accepted to represent a specific state of matter which cannot be explained at the current level of scientific knowledge. Electric charge is quantized, meaning that charge can only have discrete values. An elementary charge is denoted as e, and approximately equals 1.602·10-19 C. The electron bears a charge of -e and it is a negatively charged particle. In contrast, a proton is a positively charged particle, bearing a charge of +e. An intuitive way to understand the quantized nature of charge is to imagine an electrically neutral object as a box containing an equal number of protons (positive charges) and electrons (negative charges). Protons are fixed and cannot be taken out or added to the box. Since the number of protons and electrons is equal, the total sum of the electric charge inside the box is zero for electrically neutral objects. In order to make the object negatively charged, the only way to do so is to somehow add more electrons into the box. As electrons are indivisible particles, it is only possible to add an integer number of electrons – one cannot add half an electron into the box. As a result, the total charge of the object is N times the charge of a single electron, which equals -e·N, where N is an integer number. Similarly, in order to make an object positively charged, it is necessary to remove N electrons from the box and the [… read more]

What is an electric field? An electric field is a special state that exists in the space surrounding an electrically charged particle. This special state affects all charged particles placed in the electric field. The true nature of electric fields, as well as the true nature of an electric charge is still unknown to scientists, but the effects of an electric field can be measured and predicted using known equations.  Just like a magnet creates an invisible magnetic field around it, which can be detected by placing a second magnet in its field and measuring the attractive or repulsive force acting on the magnets, electric charges create an electric field which can be detected by using a test charge. When a test charge is placed inside an electric field, an attractive or repulsive force acts upon it. This force is called the Coulomb force. In fact, magnetic and electric fields are not entirely separate phenomena. A magnetic field that changes with time creates – or “induces” an electric field, while a moving electric field induces a magnetic field as a direct consequence of the movement. Because these two fields are so tightly connected, the magnetic and electric fields are combined into one, unified, electromagnetic field. Electric field definition The electric field can be defined as a vector field which describes the relationship between the charge of a test particle introduced in the field and the force exerted upon this charged test particle.  Where E is the electric field, F is the force exerted on the test particle introduced into the field and q is the charge of the test particle. The unit for electric field is volts per meter [V·m-1] or newtons per coulomb [N·C-1]. The application of electric field in capacitors Electromagnetism is a science which studies static and [… read more]