There are a lot of circuit diagrams and other diagrams to be practised from the chapter current electricity. The essential diagrams are prepared in the following file for ready use. You may take a printout of the file for practice.
When you draw the diagram, don’t draw freehand diagrams. Use geometrical instruments and pencil. The diagram should be neat and perfect. At the same time, you should not be consuming lot of time in perfecting the diagrams at the cost of answers to other questions.
In order to draw diagrams perfectly consuming very less time, it is necessary to practise all the diagrams well in advance. the file given below is a collection of all diagrams from the chapter current electricity as per the NCERT textbook.
Electricity is the most widely used form on energy because it is most efficiently distributed and transported. Also it can be easily converted to other forms of energy like mechanical energy, heat energy etc. Also since it is one of the fastest forms of usable energy it is used in logic digital circuits for computation since it gives the fastest results. It is this versatility of electricity that makes it so useful for modern life.
Of course electrical energy has various forms as well. It can be stored charge, alternating current or direct current. Each of these forms of energy have different advantages. Now we know that most of power that we get in our homes is in the form of AC. However it is not necessarily the most used form of energy. In fact most electronic equipment use DC power and converts AC from the supply to DC. Then why is it made AC in the first place. Let us discuss that shall we?
An inductor is merely, a wire wound to form a coil. It is a passive two
terminal device or electrical component which has the capability to store energy in magnetic field.
Varying the current flowing in the inductor with time produces or induces a voltage in the coil in accordance with the faraday’s law of electromagnetic induction which states that an EMF proportional to the rate of change of magnetic flux is induced in the coil or the closed circuit . This voltage according to the Lenz’s Law opposes the change in current which created it.
Inductors are the basic electrical components used in electric circuits which require the value of the current and voltage flowing through it to be changed with time. Inductors possess properties to delay and reshape the alternating current.
How an inductor works? Let us consider a circuit with a battery , a switch , a light bulb , a coil of wire wound around a piece of Iron . The coil of wire used here is an inductor with an Iron core. Now if we take this circuit without the inductor, the bulb lights up normally but if the inductor is taken into consideration the behavior of the circuit is totally different.
The light bulb acts as a resistor .The wire used here has a low resistance and one can expect that the current shall follow the low resistance path and bulb will be very dimly lit up. But what happens is that when we close the switch the bulb burns brightly and gets dimmer. When the switch is open the bulb lights up brightly and turns off quickly.
This happens due to the presence of inductor.
When current flows into the coil, a magnetic field is set up. While this field is developing, the coil stops the flow of current and allows the current to flow once the field is setup. When we open the switch, magnetic field present keeps the current flowing in the circuit and this current goes off as the magnetic field in this coil collapses.
This shows the fact that the inductor stores energy in the magnetic field and the inductors resist any change in the value of current flowing through it.
HenryStandard unit of inductance is Henry. Named after a scientist Joseph Henry who discovered electromagnetic induction with Faraday.
Capacity of an inductor depends upon the following four factors
Number of coils – More the number of coils more is the inductance.
The Material around which the coil is wrapped (core)
Cross Sectional Area of the coil – Larger the area, more the inductance.
Length of the coil –smaller the coil, more the inductance as smaller coil means narrower coils.The formula for calculating the capacity of an inductor is given by
H= 4π X number of turns X area of coil X mu / coil lengthwhere mu is permeability of core. Permeability of air is 1 while that of steel is 2000.
Applications Of Inductors
Used extensively in analog circuits and processing of the signal.
Along with capacitors in many tuning circuits.
Used in transformers to have coupled magnetic flux from two or more inductors.
In switch mode power supplies, inductors are used to store energy.
In electrical transmission systems to reduce the voltage from lightning strikes and to limit switching as well as fault currents.
We will publish here the portions one cannot afford to miss while preparing for the CBSE class 12 Physics Examination
The Chapters will be posted below. On Clicking the name of the chapter a new page will open. On that page there will be a set of collected questions. On clicking the questions, the complete solution to the questions will open.
Please note that this system is under preparation. We hope to complete this within a month. The link will be activated only after completing the project.