A closed circuit of conductive material provides a path for electrons to continuously flow. The charges are propelled by an electric field. We need a source of electric potential (voltage), which pushes electrons from a point of low potential energy to higher potential energy.

They flow lengthwise through the wire from one end to the other end. They move because electrons are gathered at the negative end of an electrical source looking for a way to get to the positive end of the source..

The flow of electrons in a circuit is called the electrical current.

Voltage

When a negative charge is brought near one end of a conductor electrons are repelled. When electric voltage is applied, an electric field within the metal triggers the movement of the electrons, making them shift from one end to another end of the conductor. Electrons will move toward the positive side.

The current in a parallel circuit splits into different branches then combines again before it goes back into the supply. When the current splits, the current in each branch after the split adds up to the same as the current just before the split.

Direction of conventional current is positive to negative. Electrons flows from Negative to positive.

Applying DC voltage on the capacitor no conduction current flows through the capacitor if its insulating medium is perfect insulator. This current is termed also the capacitive current. It flows because of changing electric displacement D with time.

When current flows into a capacitor, the charges get “stuck” on the plates because they can’t get past the insulating dielectric. Electrons — negatively charged particles — are sucked into one of the plates, and it becomes overall negatively charged.

Capacitor is like a bucket which is storing electrostatic energy , as a constant voltage or current is there to provide the energy . As the charge inside the capacitor increases exponentially more the current passing through the capacitor will decrease because it won’t allow any current to pass through it.

As we know that Capacitor blocks DC and allows AC to flow through it (we will discuss it in the next session that how does it happens). So it is used to separate AC and DC signals (also used in the filter circuits for the same purpose).

Either AC or DC currents can cause fibrillation of the heart at high enough levels. This typically takes place at 30 mA of AC (rms, 60 Hz) or 300 – 500 mA of DC. Though both AC and DC currents and shock are lethal, more DC current is required to have the same effect as AC current.

4 Answers

1. Power Supply Smoothing. This is the easiest and very widely used application of a capacitor.
2. Timing. If you supply power to a capacitor through a resistor, it will take time to charge.
3. Filtering. If you pass DC through a capacitor, it will charge and then block any further current from flowing.

When the capacitor is connected to the DC voltage source, initially the positive terminal of the DC supply pulls the electrons from one terminal and pushes the electrons to the second terminal. Now if the DC voltage is increased the capacitor will get damaged. …

i.e., capacitor offers infinite resistance to d.c. and hence block it. Therefore, a.c. can pass through the capacitor.

AC capacitors will not work in a DC circuit. Capacitors work where electrons slowly flow through the dielectric within a resistor. This requires a frequency. DC power does not have a frequency.

Alternating current (A.C) is five times more dangerous than Direct current (D.C). The frequency of the alternating current is the main reason for this severe effect on the human body. At this frequency, even a small voltage of 25 volts can kill a person.

220 volt a.c. means the effecitve or virtual value of a.c. is 220 volt, i.e., Ev=220 volt. But 220 volt d.c. has the same peak value (i.e., 220 volt only). Moreover, the shock of a.c. is attractive and that of d.c. is repulsive. Hence 220 volt a.c. is more dangerous than 220 volt d.c.

Many devices in your house need DC. When you plug things into the outlet in your house, you don’t get DC. Household outlets are AC – Alternating Current. This current has a frequency of 60 Hz and would look something like this (if you plotted current as a function of time).