The document discusses several topics: sex ratio, defined as the proportion of males to females in a population; electricity production through motion of charges like electrons; and deforestation which occurs when forest area is reduced below 25% of land area. Deforestation has disadvantages like increased flooding, pollution and wildlife habitat destruction, but provides materials for industry and a source of energy. Forests play an important role in the water cycle.

2. Topic name
 Sex ratio
 Production of Electricity
 DEFORSTATION

3. Sex Ratio
 Sex Ratio—Proportion of males relative to females in a population
 General formula:
SR = Number of males/Number of females*100

4. Sex Ratio:
Males population= Pm
Females Population=Pf
Total population=Pt
Pt=Pm +Pf

5. Sex Ratio of Births
 Sex Ratio of Births
 Sex Ratio of Births—Number of male births per 100 female births
=Number of male births/Number of female births*100
 Ratio < 100 →More female than male births
 = 100 → Same number of male and
female births
 > 100 → More male than female births

6. Sex Ratio of Deaths
 Sex Ratio of Deaths:
 Sex Ratio of Deaths—Number of male Deaths per 100 female Deaths
=Number of male Deaths/Number of female Deaths*100
 Ratio < 100 →More female than male Deaths
 = 100 → Same number of male and
 female Deaths
 > 100 → More male than female Deaths

7. Sex Ratio of Migrants
 Sex Ratio of migrants:
 Sex Ratio of Migrants—Number of male Migrants per 100 female
Migrants
=Number of male Migrants/Number of female Migrants*100

8. What is Electricity?
Electricity is the form of energy
that can be easily changed to
other form.

9. 2) Production of Electricity
 Electricity by definition is electric current that is used as a power
source!
 This electric current is generated in a power plant, and then sent out
 over a power grid to your homes, and ultimately to your power
outlets.

10. Electricity
 Electricity is very important in our lives.
 We would find it very hard to do without it.
 There are so many things in our homes that are powered by
electricity that we have begun to depend on them.
 Imagine you woke up this morning and had no electricity.
What difference would it make to
your normal morning routine?

11.  The movement of charges such
as electrons is called current, and
this electrical current is what
powers household appliances.
 Electric Current =Charge Passing
Through A Given Area
-------------------------------
Time

12.  Electric current generation - whether from fossil fuels, nuclear,
renewable fuels, or other sources is usually
based on the:

13. If you place a magnet and a
conductor (copper wire), in a room
together
 there will be no electric current generated.
 This is because motion, from our equation for electricity, is
missing!
 An electric current is not generated unless the magnetic field
is moving
 relative to the copper wire, or the copper wire is moving
relative to the
 magnetic field.

15. When the number of forest are reduced and the forested area is
curtailed, deforestation takes place. It is generally accepted that
for a balanced environment and economy about 25% of the land
area should be under forest

16. Forests are cut down to meet the demands of industry
because wood is required as construction material for
building.
In Pakistan nearly 50% of heating and cooking
requirements are met by 20.88 cubic metres of fuel wood
every year. In fact, 76% of the rural population depends
on wood for heating and cooking which results in
excessive cutting of trees.

17. Deforestation destroys the habitats of millions of
species of plants and animals that will need the
areas of forest to survive. Thus, it may lead to the
extinction of these species, causing havoc in the
biological food chains and the delicate balance
of the ecosystem of these areas.
 ppollution will be increase
Destruction of wildlife habitation

18. DISADVANTAGE:
 Flooding also causes of the deforestation.
 The removal of the tress adds to the high level of
the carbon dioxide in the atmosphere.

19. ADVANTAGES:
 Deforestation provide the material for
various industry.
 Cutting down tress provide a source
of energy.

20. ADVANTAGE:
 Tress are important to the water cycle. They
absorbs rainfall and produce water vapor that is
released in the atmosphere.
 Being deforestation we should convert forest
land into agricultural land.