Electrostatics_21

Electric charge accumulates in the highly curved surface regions of the conductor – why?

Electrostatic Properties of a Conductor (Conductors and Electric Fields)

Here you will find a set of Numericals on Coulomb’s Law for class 12. This consists of easy-to-hard Numerical questions for Physics class 12. Formulas Used |F| = k q1q2/r2 Numericals on Coulomb’s Law for class 12 Solution: given:q1 = – 2.10 x 10-6 Cq2 = + 1.50 x 10-6 Cr =3.3 x 10-2 m […]

Birds on a wire don’t get an electric shock. Let’s see why. Birds can sit on power lines without getting electrocuted, even though the wires are not insulated. For a current to flow through a bird on a wire, there would have to be a potential difference between its two feet. The wire might be […]

In this post, we will cover the definition of Gaussian surface and its examples. We will also study the properties of the Gaussian surface.

Capacitors and their usage is the topic of this post. The capacitor is a component that has the ability or “capacity” to store energy in the form of an electrical charge producing a potential difference across its plates. In other words, Capacitors are components of electrical circuits that temporarily store electric charge. Capacitors are simple […]

In this post, we have presented fundamental and conceptual questions and answers based on parallel plate capacitors and dielectrics between the plates. This Capacitor and dielectric Question set will certainly help to build the concepts. Capacitor and dielectric Question & Answer 1 ) A parallel plate capacitor is charged by a battery which is then […]

A capacitor is charged by connecting it to a battery or to a constant-voltage power supply to create a circuit. Charge flows to the capacitor from the battery or power supply until the potential difference across the capacitor is the same as the supplied voltage. If the capacitor is disconnected, it retains its charge and […]

The electrostatic field inside any isolated conductor is always zero. In a cavity in a conductor, the net charge and the electric field are always zero. Let’s see how we can say that. Note that, these are important consequences of Gauss’s Law. The electrostatic field inside any isolated conductor is always zero Let’s suppose a […]

In this post, we will see how Polarization of a Dielectric between parallel plates of a capacitor happens with the help of an external electric field. The potential difference V0 between the plates of a capacitor is reduced to V0/K when a dielectric is introduced. K is the dielectric constant. The potential difference is reduced […]

In this post, we will solve a numerical problem on the dielectric strength and dielectric constant of capacitor, maximum electric field, maximum potential difference, maximum charge, etc. Numerical problem on dielectric strength & dielectric constant – solved Question: A parallel-plate capacitor has plates of dimensions 2.0 cm by 3.0 cm separated by a 1.0-mm thickness […]

An electrolytic capacitor is often used to store large amounts of charge at relatively low voltages. Structure of electrolytic capacitors | dielectric formation This device, shown in Figure 1, consists of a metallic foil in contact with an electrolyte. Electrolyte is a solution that conducts electricity by virtue of the motion of ions contained in […]

Dielectric strength of a dielectric is the maximum electric field that the dielectric can withstand with its insulating properties intact. In other words, the dielectric strength equals the maximum electric field that can exist in a dielectric without electrical breakdown. If the magnitude of the electric field in the dielectric exceeds the dielectric strength, then […]

Series Combination of capacitors Two capacitors connected as shown in Figure 1a and the equivalent circuit diagram in Figure 1b are known as a series combination of capacitors. The left plate of capacitor 1 and the right plate of capacitor 2 are connected to the terminals of a battery. The other two plates are connected […]

Parallel Combination of capacitors Two capacitors connected as shown in Figure 1a are known as a parallel combination of capacitors. Figure 1b shows a circuit diagram for this combination of capacitors. The left plates of the capacitors are connected by a conducting wire to the positive terminal of the battery and are therefore both at […]

In this post, we will derive the equation of the Energy density in charged parallel plate capacitor. Energy stored in parallel plate capacitor U = (1/2) C V2 where, C is the capacitance of the capacitor and V is the potential difference between the two parallel plates of the above said capacitor. We know, that […]

Energy stored in combination of Capacitors equals the sum of the energies stored in individual capacitors. Let’s see how we can show this mathematically using equations. To find out the Energy stored in combination of Capacitors, we need to find out the equivalent capacitance (Ceq) and use this value in the equation of stored energy. […]

Defibrillator – application of Capacitors in the medical field One gadget in which capacitors play a significant role is the defibrillator. A defibrillator has a large capacitor and when it is fully charged it can store a Maximum of 360 Joule of energy in its electric field. The defibrillator is quite fast to deliver all […]

In this post, we discuss the concept of voltage (or Potential Difference) in terms of work done in separating charges. Moving charges give rise to electricity. For charges to move, there must be some force to be applied on these charges, and this force can be caused by other positive or negative charges. Consider the […]

At a point between two plates of the parallel plate capacitor, the Electric field generated by the combined effect of the 2 plates of the capacitor can be expressed as: E = σ /2 ε0 + σ /2 ε0 = σ / ε0 [ note that the electric field produced by a plane sheet of […]

When a charged rubber rod is brought close to a thin stream of water, the water is attracted toward the rod and the stream is bent. Water molecules have a permanent separation of charge or regions of different charges. Such molecules are called polar molecules. Charged rod brought close to a small stream of water […]

Touch screens are quite common these days. In this post, we will discuss the physics behind the working principles of different touch screens. Specifically speaking, we will cover here the working principles of Resistive Touch Screens and Capacitive Touch Screens. Resistive Touch Screens One of the most common touch screens we experience is found at […]

When a negatively charged rubber comb is brought near small pieces of paper, the charges in the paper molecules are acted on by electric forces – positive charges are attracted, negative charges repelled – and the result is an effective separation of charge. The molecules are then said to be polarized: they possess definite regions […]

A bunch of important formulas related to Capacitance & capacitors are listed below. capacitance of a conductor & capacitance of a spherical conductor – formulas capacitance of parallel plate capacitors with or without dielectric slab, Potential energy – formulas equivalent capacitors, redistribution of charge – formulas

Principle of a capacitor The principle of a capacitor is based on two physical events. These are as follows: 1 ) The capacitance of a conductor increases by a small amount when another uncharged conductor is placed near it.2 ) The capacitance of a conductor increases greatly when an earth-connected conductor is placed near it. […]

In this post, we will discuss and derive the formula of the Capacitance of a Spherical Conductor. derivation of the Capacitance of a Spherical Conductor Suppose an isolated spherical conductor of radius a metre is placed in a vacuum (or air). Suppose a charge of +Q coulomb is given to the sphere. The charge spreads […]

Consider two infinite plane parallel sheets of charge A and B, having surface charge densities equal to σ1 and σ2 respectively. (see the figures 1 to 4 in the following sections). Note that, In a sheet of charge, the same charge shows up on its two sides. On the other hand, since a plane & […]

In this post, we will take a few cases where the Equilibrium of electric forces on charges on one line happens. In every case, there are 3 charges on one line. We will list down the specific equilibrium condition of each such case and the formula of equilibrium for that scenario. Scenario 1 (Equilibrium of […]