Electricity & Megnetism

What is toroid? The solenoid bent into circular shape is called toroid. Inductance of a toroid derivation Consider a toroid having rectangular cross sectional area.The inner radius of the toroid is ‘a’ while outer radius is b.The number of turns of toroid is N.Let i be the current flowing through each turn of toroid. The magnetic field lines inside the ...

Chemical effects of current Voltmeter or coulomb meter: The vessel in which electrolytes is carried out.It is also called electrolytic cell. Electrolyte: An ionic compound in aquas solution or molten state is called an electrolyte. Electrolysis: On passing current through an electrolyte,chemical changes occur in electrolyte and substances are liberated at the electrodes.This process is called electrolysis. Faraday’s laws: First ...

Energy stored in capacitor equation Consider a capacitor with the capacitance ‘C’ ,which is connected to the battery of emf ‘V’ .If ‘dq’ charge is transferred from one plate to other,then the work done ‘dW’ will be: dW =V dq This work done is stored in the form of electric potential energy ‘dU’ dU =V dq When the capacitor is ...

Capacitance with dielectric formula Consider a parallel plate capacitor which is connected with a battery of emf ‘V’ .Let ‘A’ is the area of each plate and ‘d’  is separation between the plates. If ‘q’ charge is stored in the capacitor when there is vacuum or air as medium between the plates ,then: q= CV Where ‘C’ is the capacitance ...

Formula of equivalent capacitance in series Series combination when capacitors are connected in series,the total capacitance is less than the smallest capacitance value because the effective plate separation increases.The calculation of total series capacitance is analogous to the calculation of total resistance of parallel resistors. This type of combination has the following characteristics: Each capacitor has the same charge across ...

Thermistor definition A thermistor is a type of  variable resistor that is temperature sensitive . How thermistor works? When its temperature coefficient is negative,the resistance changes inversely with temperature. When its temperature coefficient is positive the resistance changes directly with temperature. The resistance of a photo-conductive cell changes with a change in light intensity.This cell also has a negative temperature coefficient. Symbols for ...

Step up transformer: If (Ns greater than NP) and (Vs is greater Vp) such a transformer in which voltage across secondary is greater than the primary voltage is called a step up transformer.A step up transformer has more turns in its secondary winding than its primary winding and is used to increase the ac voltage. The turns ratio for a step up ...

  Induced EMF and Induced Current There are many ways to produced induced emf figure illustrated one of them. Consider a straight piece of wire of length l placed in the magnetic field of a permanent magnet. The wire is connected to a sensitive galvanometer. This forms a closed path or loop without any battery. In beginning when the loop  ...

Magnetic Flux (Φ) definition The group of force lines going from the north pole to the south pole of a magnet is called the magnetic flux, symbolized by Φ (the Greek letter phi). The number of lines of force in a magnetic field determines the value of the flux. The more lines of force, the greater the flux and the stronger the ...

Coulomb’s law Newton’s law of gravitation Comparison of Coulomb’s law and Newton’s law of gravitation The electrical force between two charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them:It is expressed The gravitational force between two masses is directly proportional to the product of their masses and inversely ...