• Skip to main content
  • Skip to primary sidebar
  • Skip to footer
  • NCERT Solutions
    • NCERT Books Free Download
  • TS Grewal
    • TS Grewal Class 12 Accountancy Solutions
    • TS Grewal Class 11 Accountancy Solutions
  • CBSE Sample Papers
  • NCERT Exemplar Problems
  • English Grammar
  • MCQ Questions

CBSE Tuts

CBSE Maths notes, CBSE physics notes, CBSE chemistry notes

NEET Physics Notes Electrostatics-Electric Cell

NEET Physics Notes Electrostatics-Electric Cell

Electric Cell

Electric Cell

An electric cell is a device which maintains a continuous flow of charge (or electric current) in a circuit by a chemical reaction. In an electric cell, there are two rods of different metals called electrodes.

Types of Electric Cell

There are two basic types of electric cell

Primary Cell

A cell is called primary, if it used only for discharge. The current leaves the cell at the positive (+ve) terminal goes through the external circuit and enters the cell at the negative (-ve) terminal. Examples of primary cells are daniell cell, laclanche cell and dry cell.

Dry cell

The most popular cell is dry cell. It is a special type of laclanche cell in which ‘ both NH4Cl are MnO2 are are prepared in the form of a paste. The paste is contained which is negative electrode. The internal resistance of a dry cell is very small generally NEET Physics Notes Electrostatics-Electric Cell 1 Its emf is generally 1.5 V.
NEET Physics Notes Electrostatics-Electric Cell 2
Secondary Cell

In a secondary cell, the current pass in both directions When current leaves the cell at the positive (+ve) terminal and enters the cell at the negative (-ve) terminal, the cell is discharge. This is ‘ called normal working of the cell. In this case, the chemical energy is converted into electrical energy. The most commonly used secondary cell is a lead accumulator.
NEET Physics Notes Electrostatics-Electric Cell 3
A lead commulator consists of electrodes made of PbO 2 and Pb immersed is dil. H2S04. Discharging process, the NEET Physics Notes Electrostatics-Electric Cell 4 ions move towards Pb electrode give negative
charge and H+ ions move to the PbO 2 electrode, given up positive charge.
NEET Physics Notes Electrostatics-Electric Cell 5
The PbO so formed reacts with dil.H2S04 to get PbS0 4 and H20.

NEET Physics Notes Electrostatics-Electric Cell 6
Therefore, PbS0 4 is formed at the both electrodes. In charging process, a current forced from the positive to the negative inside the cell. The H+ ions move towards the negative electrode and react with the PbS0 4
NEET Physics Notes Electrostatics-Electric Cell 7
At the positive electrode, the reactions
NEET Physics Notes Electrostatics-Electric Cell 8

Electromotive Force (EMF) of Cell

The potential difference between the two poles of the cell in an open circuit is called the electromotive force (emf) of the cell. It is denoted by E.

Its SI unit is volt (V) or joule coloumb-1 (JC_1)

Internal Resistance

Thus, when a current is drawn through a source, the potential difference between the terminal of the source is
V = E – ir .
This can also be shown as below E r
NEET Physics Notes Electrostatics-Electric Cell 9
Following three special cases are possible

  •  If the current flows in opposite direction (as in case of charging of battery), then V = E + Ir
  •  V = E, if the current through the cell is zero.
  •  V = 0, if the cell is short circuited.
  • This is because current in the circuit
    NEET Physics Notes Electrostatics-Electric Cell 10
    NEET Physics Notes Electrostatics-Electric Cell 11

Potential Difference and Emf of a Cell

Emf of a cell is the terminal potential difference of cell when it is in an open circuit, i.e. it is not supplying any current to the external circuit. However, when it is supplying a current to an external resistance, the voltage across the terminals of cell is called the terminal voltage or terminal potential difference.
If E be the emf and r the internal resistance of a cell and a resistance R is joined with it, then current in the
NEET Physics Notes Electrostatics-Electric Cell 12
Terminal voltage is more than EMF of cell when cell is charged and it is given by V = E + Ir

Combination of Cells in Series and in Parallel

A group of cells is called a battery. Two common grouping of cells are

Series Grouping

In series grouping, if all the cells are joined so as to supply current in the same direction, then resultant emf

Eeq =E1+E2 + E3 +…

However, if one or more cells are joined so as to supply current in the reverse direction then the EMF of that/those cells is taken as negative while calculating the equivalent emf.
NEET Physics Notes Electrostatics-Electric Cell 13
The equivalent internal resistance of cell
req =r1+r2+r3 + …
If n cells, each of emf E and internal resistance r, are joined in series, then

Eeq = nE and req = nr

Parallel Grouping

In parallel grouping, if positive terminals of all cells have been joined at one point and all negative terminals at another point, then
NEET Physics Notes Electrostatics-Electric Cell 14

PhysicsChemistryBiology

Primary Sidebar

NCERT Exemplar problems With Solutions CBSE Previous Year Questions with Solutoins CBSE Sample Papers

Recent Posts

  • MCQ Questions with Answers for Class 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, and 1 all Subjects
  • Angle, Types of Angles
  • AND gate is formed by using two? 1)OR 2)NAND 3)NOT 4)NOR
  • And expression for one minus the quotient of one and a number X?
  • What is average human body temperature in Kelvins?
  • How many moles of caffeine are in a cup, and how many molecules of caffeine?
  • How far will the car have traveled in that time?
  • What is its atomic number?
  • How many neutrons does it have?
  • An atom loses electrons to form what?
  • What is the atomic number of this atom?
  • Which one of these is the answer?
  • What is its concentration?
  • Can an equilateral triangle also be isosceles?
  • What is the charge of an alpha particle?

Footer

Maths NCERT Solutions

NCERT Solutions for Class 12 Maths
NCERT Solutions for Class 11 Maths
NCERT Solutions for Class 10 Maths
NCERT Solutions for Class 9 Maths
NCERT Solutions for Class 8 Maths
NCERT Solutions for Class 7 Maths
NCERT Solutions for Class 6 Maths

SCIENCE NCERT SOLUTIONS

NCERT Solutions for Class 12 Physics
NCERT Solutions for Class 12 Chemistry
NCERT Solutions for Class 11 Physics
NCERT Solutions for Class 11 Chemistry
NCERT Solutions for Class 10 Science
NCERT Solutions for Class 9 Science
NCERT Solutions for Class 7 Science
MCQ Questions NCERT Solutions
CBSE Sample Papers
cbse ncert
NCERT Exemplar Solutions LCM and GCF Calculator
TS Grewal Accountancy Class 12 Solutions
TS Grewal Accountancy Class 11 Solutions