Chapter 1:Chemical Reaction And Equations

Chapter 2:Acids, Bases and Salts

Chapter 3:Metals and Non-metals

Chapter 4:Carbon and Its Compounds

Chapter 5: Periodic Classification of Elements

Chapter 10: Light Reflection and Refraction

Chapter 11:Human Eye and Colourful World

There are two type of electric charge

i) Positive charge

ii) Negetive charge

** Opposite charge attract each other**

** Unlike charge repel each other**

**SI unit of electric charge(Q)**: The SI unit of electric charge is coulomb(C).

An electron possessse a negetive charge of 1.6 x 10^{-19}C

A Coulomb is equal to the charge contained in 6.25 x 10^{18} electron

** Conductor:** The Substance through which electricity can flow are called conductor

**Insulator:** The Substance through which electricity can not flow are called Insulator

Current(I)=

Q
/
t

** Ammeter:** An instrument called ammeter
measures electric current in a circuit

** Direction of electric current:**

Conventionally, in an electric circuit the
direction of electric current is taken as opposite to the direction of the
flow of electrons, which are negative charges.

** Electric circuit:**

A continuous and closed path consisting of wire bulb and switch between the two terminal of a cell along which an electric current flow called an electric circuit

** ELECTRIC POTENTIAL:**

An electric potential is the amount of work needed to move a unit of electric charge from a point to a specific point in an electric field without producing an acceleration.

** Potential Difference:**

The amount of work require for moiving a unit charge particle from one point to another point in electric circuit is called Potential Difference

Work done (W)
/
Charge (Q)

V=

W
/
Q

**SI unit:** The SI unit of electric potential difference is volt (V)

**Define 1 volt:** One volt is the potential difference between two points in a current carrying conductor
when 1 joule of work is done to move a charge of 1 coulomb from one
point to the other

1 joule
/
1 coulomb

1 V = 1 J C

**Voltmeter:** The potential difference is measured by means of an instrument called
the voltmeter

**CIRCUIT DIAGRAM:**

It is often convenient to draw a schematic diagram, in which different
components of the circuit are represented by the symbols conveniently
used.

**OHM’S LAW:**

It's stated that the electric current flowing
through a metallic wire is directly proportional to the
potential difference V, across its ends provided its
temperature remains the same. This is called Ohm’s law

** **

or V/I = constant

= R

or V = IR

**Resistance:** It is the
property of a conductor to resist the flow of charges through it

**SI Unit of Resistance:** Its SI unit is ohm(Ω)

,
**R = V/I**

**Define 1 ohm:** If the potential difference across the two ends of a conductor is 1 V
and the current through it is 1 A, then the resistance R, of the conductor
is 1 Ω

1 volt
/
1 ampere

here I=

V
/
R

**variable
resistance: **A component used to
regulate current without changing the voltage source is called variable
resistance

** Factor effecting the resistance of a conductor: **

The resistance of the conductor depends on following:

(i) on its length

(ii) on its area of cross-section,

(iii) on the nature of its material

a) Resistance of a given conductor is directly proportional to its lenght

b) Resistance of a given conductor is inversely proportional to the area of cross-section (A)

1
/
A

Combining above we ge

l
/
A

l
/
A

** Resistivity: **A measure of the resisting power of a specified material to the flow of an electric current.

R x A
/
l

**SI Unit of Resistivity: ** The SI unit of resistivity is
Ω m.

**Combination of resistances: **

There are two type of combination of resistances**1) Series: ****ii) Parallel: **

**1) Resistors in Series: **

The number of resistances are joined end to end. Here the resistors are said
to be connected in series.

As show in fig Three resistance R_{1},R_{2},R_{3} With potential difference across resistance is
V_{1},V_{2},V_{3} respectily connecting in series with battery of V volts has been applied to the end of this series combination

Now

That is the total potential difference
across a combination of resistors in series is equal to the sum of potential
difference across the individual resistors

V = V_{1} + V_{2} + V_{3} ..............(1)

According to ohm's law

V
/
I

Or, V =I x R .................(2)

So ,

V

V

V

On putting equation 2,3,4 and 5 in equation 1

I x R =I x R

= I x ( R

We get

R= R

the resistance of the combination R equals the sum of their individual resistances R

**Resistors in Parallel: **

As show in fig Three resistance R_{1},R_{2},R_{3} are connecting parallel to another between the same two point A and B battary of V volt applied across the end of this combination.

the total current I, is equal to the sum of the
separate currents through each branch of the combination.
I = I_{1} + I_{2} + I_{3}

Let R be the equivalent resistance of the parallel combination of
resistors.

By applying Ohm’s law

V
/
R

----------------------1I

V
/
R_{1}

,
I
V
/
R_{2}

,
I
V
/
R_{3}

------------------------2On putting Equation 2 in 1

I
/
R

=
V
/
R_{1}

+
V
/
R_{2}

+
V
/
R_{3}

we get

1
/
R

=
1
/
R_{1}

+
1
/
R_{2}

+
1
/
R_{3}

**Note ** the reciprocal of the equivalent resistance
of a group of resistances joined in parallel is equal to the sum of the
reciprocals of the individual resistances.

**1) Disadvantage of a series : **

i) when one
electrical appliance fails the circuit is broken and none of the electrical appliance works

ii) In series circuit all electric appliance connected only one switch So we can not turn of separately.

iii) Do not get eqaul volt of each electric appliance

** Advantages of a parallel : **

i) a parallel
circuit divides the current through the electrical gadgets

ii)Each electric appliance get eqaul volt

** HEATING EFFECT OF ELECTRIC CURRENT : **

When an electric current passed through a high resistance wire its becomes hot and produce heat. this Known as Heating effect of current

. The work done in moving the charge Q through a potential difference V is VQ. Therefore, the source must supply energy equal to VQ in time t.

SO , W = V x Q -----1

here Q = I x t ---------(2)

from Ohm's law

V
/
I

So, V= R x I -------------(3)

From equation 2 and 3 in 1 ,we get

W = I x t x I x RSo, Work done W = I

for a steady current I, the amount of heat H produced in time t is

The law implies that heat produced in a resistor is

i)) directly proportional to the square of current for a given resistance

(ii) directly proportional to resistance for a given current

(iii) directly proportional to the time for which the current flows through the resistor

**Applications of Heating Effect of
Electric Current : **

i)The electric laundry iron, electric toaster, electric oven, electric kettle and
electric heater are some of the familiar devices

ii)The electric heating is also used to produce light, as in an electric
bulb

iii) The heating effect of current is utilised in electric fuse for protecting household wiring and electric appliance

**tungsten is used for making bulb filaments because it has high melting point**

** ELECTRIC POWER : **

the rate of doing work is
power This is also the rate of consumption of energy.

Work done
/
Time taken

or,

P =

W
/
t

Or, P = I

V^{2}
/
R

**SI UNIT ELECTRIC POWER : **The SI unit of electric power is watt (W).

**Define one watt: **The power of 1 watt is a rate of working of 1 joule per second

1 joule
/
1 second

**The commercial unit of electric energy: **The commercial unit of electric energy
is kilowatt hour (kW h), commonly known as ‘unit’.

1 kW h = 1000 watt × 3600 second

= 3.6 × 106 watt second

= 3.6 × 106 joule (J)

Chapter 1:Chemical Reaction And Equations

Chapter 2:Acids, Bases and Salts

Chapter 3:Metals and Non-metals

Chapter 4:Carbon and Its Compounds

Chapter 5: Periodic Classification of Elements

Chapter 10: Light Reflection and Refraction

Chapter 11:Human Eye and Colourful World