Q.1: Explain the different types of First Aid. Q.2: Explain the properties of conductors and insulators. Q.3: A resistor is connected in series with parallel circuit comprises of two resistances of 12 Ω and 8 Ω. Total power dissipated in the circuit is 70 watts when the applied voltage is 20 volts. Calculate value of resistance. Q.4 What are the characteristics of primary and secondary cells? Q.5 What defects occur in the secondary cell? Q.6 Describe the working principle of alkaline cell. Q.7 What are the advantages and disadvantages of AC current? Q.8 What is difference between ammeter, voltmeter, ohmmeter and multimeter? Q.9 Discuss the working principle of moving coil instruments. Q.10 State the efficiency and protective devices of transformer.

1. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Faculty of Engineering
Department of Mining Engineering
Assignment
Class: BS (Mining) Semester 3rd
Date: 27.12.2013
Course: Basic Electrical Technology Instructor: Muhammad Bux

2. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Name: Ghulam Mehdi Roll No: 23101
Q.1: Explain the different types of First Aid.
Ans: Emergency treatment given before regular medical services can be obtained is known as First Aid.
There are six types of First Aid Training.
1. First Aid & Cardio-pulmonary Resuscitation:

3. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
First Aid and Cardio-Pulmonary Resuscitation are the most common first aid training that everyone should
learn, whether you are a teenager or a senior citizen, whether you are an office worker or a business owner.
In this first type, one should learn about the different techniques such as Cardio-pulmonary Resuscitation
protocols, caring for open wounds, burns, and fractures. The use of Automated External Defibrillators may also
be included in this training. As a matter of fact, most of the workplaces today require occupational first aid and
Cardio-pulmonary Resuscitation trainings.
2. Trainings for Sports Safety:
This type of first aid training wanted to train individual to treat injuries that will happen in the sports fields,
such as fractures, sprains, and contusions, to name a few. Also, sports safety trainings give appropriate
instructions to minimize possible injuries to occur. Coaches and athletes are the most common audiences of
this type of training.

4. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
3. First Aid Emergency:
First aid emergency is a training that educates individual to help during emergencies such as providing utmost
care for victims who may be seriously injured and the appropriate ways to do it. This type of training may also
include Cardio-Pulmonary Resuscitation trainings. All can freely participate in this type of training especially
those whose work are accompanied with many emergencies.
4. Trainings for Babysitters:
Training for babysitter is basically intended of older children, 11-15 years old. This involves basic first aid
trainings for babysitting tasks.
5. Children First Aid:

5. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
In learning first aid, being young is not an excuse to learn care principles; you can enroll your kids in this type
of training. Numerous first aid for children trainings are already designed for children who are five (5) years
and above, these includes basic care principles that children can easily understand and apply.
6. Pet First Aid:
If you have pets at home and you love them so much, then consider this type of training and learn various ways
in taking care for your little ones. This training teaches you how provide utmost care to your pets especially
when they are choked, when they have wounds and sprained limbs.

6. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

7. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

8. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
If the person does not breathe then immediately arrange artificial method of breathing.
There are three methods of artificial breathing.
1-Holger Nelson Method:
The victim should be kept in the bed facing the ground. Fold his hands & keep it in the backside of his head,
the helper sitting at his head should massage his back using both hands. This is done with in two seconds.
2-Mouth to mouth:
In this method the helper pushes air by keeping his mouth on the victim’s mouth. By closing his nose then the
air fills lungs. So the victim gets artificial respiration.
3-Through Nose:

9. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
In this method the helper send air through victim’s nose. By closing his mouth the air is blown in his nose till
the heart of the victim rises by this way the victim gets artificial respiration. For a child the air blown is half the
heart level, compared to adult.
Q.2: Explain the properties of conductors and insulators.
Ans: Conductors are made of materials that electricity can flow through easily.
• These materials are made up of atoms whose electrons can move away freely.
• An object made of a conducting material will permit charge to be transferred across the entire surface of
the object.
• A conductor is a material which allows the easy passage of current through it.

10. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
• In a conductor the energy band gap is absent, that is, the valance and conduction bands overlap each
other.
• Hence even when a very small amount of energy is applied to the material the electron is excited from
the valance to conduction band.
• This results in the easy conduction of electricity.
• Some examples of conductors are:
Copper, Aluminum, Platinum, Gold,Silver,Water, People and Animals etc.
Insulators are materials opposite of conductors.
• The atoms are not easily free and are stable, preventing or blocking the flow of electricity.

11. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
• When a voltage is placed across an insulator, no current flows.
• Electrical insulation is the absence of electrical conduction.
• Insulators are characterized by having a large energy band gap. This is because the filled valence band
is very distant from the empty conduction band.
• For conduction to take place electrons must be transferred from the valance band to the conduction
band. Since the energy band gap is very high for insulators huge amount of energy has to be given to
the material to excite an electron so that it reaches the conduction band.

12. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
• Some examples of insulators are:
Glass,Porcelain,Plastic,Rubber etc.

13. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

14. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Q.3: A resistor is connected in series with parallel circuit comprises of two resistances of 12 Ω and 8 Ω.
Total power dissipated in the circuit is 70 watts when the applied voltage is 20 volts. Calculate value of
resistance.
Ans: Given Data:
R1=12Ω
R2=8Ω

15. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Power=70W
Voltage=20V
Resistance(R) =?
Sol:
We know that in parallel circuit the resistance can find by:
1/RT=1/ R1+1/ R2
Putting values’

16. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
1/RT=1/12+1/8
=(2+3)/24
=5/24
RT=24/5
RT=4.8Ω…………………Ans.

17. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Q.4 What are the characteristics of primary and secondary cells?
Ans:
o Primary Cells:
oPrimary cells are the non-rechargeable cells
• These cells produce electrical energy by themselves.

18. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
• Once they are used up, they have to be discarded & can't be recharged.
• In fact, their electrolyte can't undergo a reversible reaction. That is the reason it is not possible to
recharge them.
• Their life is short.

19. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
• They have low power output and low efficiency.

20. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

21. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
• It has weightless and low cost.
• Less maintenance required as compared to secondary cell.
• Some examples are :
o Dry cells (Zinc-carbon cells),
o Leclanche cell
o Daniel cell.

22. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
o Secondary Cells:
Secondary cells are rechargeable.
• Their electrochemical reactions can be reversed.
• Externally supplied electrical energy is stored in the form of chemical energy & the cell is "charged"
and recharged again and again.

23. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

24. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

25. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

26. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
• A secondary cell can undergo a limited number of such charge-discharge cycles.
• Their life is long.
• They have high power output and high efficiency.

27. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
• It has heavy weight and costly.
• High maintenance required as compared to primary cell.
• Some examples are:
o (i)-Lead acid battery,
o (ii)-Li-ion battery,
o (iii)-Ni-MH (Nickel metal hydride) battery.

28. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Q.5 What defects occur in the secondary cell?
Ans:There are Three types of defects occurs in the secondary battery. These are:
1-Sulphation.
2-Sedimentation
3-Plates buckling.
1-Sulphation:

29. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Lead–acid batteries lose the ability to accept a charge when discharged for too long due to sulphation,
the crystallization of lead sulfate.
2-Sedimentation:
When the particles deposited on the positive plate dissolves in the electrolyte, short circuit may occur.
If it happens the electrolyte should be changed.
3-Plate Buckling:

30. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
The plates become unshaped due to high rate of charging& discharging.
Q.6 Describe the working principle of alkaline cell.

31. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Ans: The main working principle of the alkaline batteries is based on reaction between zinc (Zn) and
manganese dioxide (MnO2). Alkaline battery is so named because the electrolyte used in it is potassium
hydroxide, a purely alkaline substance.
In an alkaline battery cell, the powder zinc serves as anode, manganese dioxide serves as cathode and
potassium hydroxide serves as electrolyte.
First half reaction is

32. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Second half reaction is

33. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

34. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

35. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

36. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Overall reaction

37. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
An alkaline battery cell is rated for 1.5 V. The average voltage under load condition may be 1.1 to 1.3
V. An alkaline cell is generally rated for 700 mA.
Q.7 What are the advantages and disadvantages of AC current?
Ans:
Advantages:

38. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
• AC is easier to generate especially 3 phase for high power.
• With transformers it is easy to raise the voltage to higher levels which make the transmission easier.
• The higher voltage requires less current and would result in lower losses than higher current
transmission.
• AC can be more easily switched because the voltage is zero many times per second.
• All domestic appliances are designed to use AC.
• It can travel a farther distance than DC.
• The main advantage of AC is that it is more economical to transport.
Disadvantages:

39. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
• Transmission lines have inductance and resistance which causes voltage drops and losses.
• The inductance causes a voltage drop with AC.
• Transmission lines that are as long as 10 percent (300 miles) or more of the 60 Hz wavelength (5,000
KM or 3,000 miles) radiate energy and thus have radiation losses.
• 60 Hz is the same frequency as the human body. It can kill you.
Q.8 What is difference between ammeter, voltmeter, ohmmeter and multimeter?

40. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Ans:
Ammeter:
An ammeter is an electrical instrument which is used to measure current in amperes.
Voltmeter:
A voltmeter is an electrical instrument which is used to measure the potential difference in
volts between two points.
Ohmmeter:

41. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
An ohmmeter is an electrical instrument which is used to measure resistance in ohms.
Multimeter:
A multimeter is an electrical instrument which is used to measure current in amperes,
potential difference in volts and resistance in ohms.
Q.9 Discuss the working principle of moving coil instruments.
Ans:Moining coil instruments:

42. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
This type of instruments is based on the principle of permanent magnet moving coil mechanism i.e when a
current carrying conductor is placed in a magnetic field, mechanical forces acts on the conductor. The coil
placed in magnetic field and carrying current is attached to the moving system .With the movement of the coil
the pointer moves over the scale.
Construction:
It consists of a powerful magnet with soft iron piece and light rectangular coil of many turns of fine wire
wound on aluminum former inside which is an iron core .A permanent magnet provides a uniform magnetic
field into which a spring-mounted moving coil is positioned. A pointer is attached to the moving coil. The
current to be measured passes through the coil, which is free to pivot. As the current passes through the coil, it

43. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
produces a magnetic field that interacts with the uniform magnetic field produced by the permanent magnet.
This interaction causes the moving coil and pointer to rotate.

44. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

45. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Q.10 State the efficiency and protective devices of transformer.
Ans :Transformer:

46. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
A transformer is a four-terminal device that transforms an AC input voltage into a higher or lower AC output voltage.
Transformers are not designed to raise or lower DC voltages.

47. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

48. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Efficiency of transformer:
Efficiency of a device is equal to the ratio of output to input.
Since,

49. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Output = Ps
or
Output = Vs Is
and
Input = Pp
or
Input = Vp Ip
Efficiency = output / input

50. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Efficiency = Ps / Pp
Efficiency = Vs Is / Vp Ip
Efficiency in percent = (Vs Is / Vp Ip) x 100.
In actual practice output is not equal to input therefore actual transformers are not 100% efficient. However
commercial transformers have very high efficiency in the range of 95% to 99%.
There are four main protective devices of transformer which are given below:

51. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
1-Conservator
2-Breather
3-Explosion vent
4-Bucholz relay
1-Conservator:

52. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
The conservator is a cylindrical vessel. It is fitted on the top of the tank. Tank is filled with oil but
conservator filled with oil partly.
2-Breather:
It is a small vessel. It is connected between conservator & air outlet. It contains silica gel. Silica gel color is
blue when dry and pink when wet.
3-Explosion vent:

53. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta
Explosion vent is fitted on the top of the tank .It protect the tank by the explosion and high pressures of
gases. Under normal condition air is not allowed to come in contract with oil. The gas is expelled through
explosion vent in to atmosphere. The explosion vent’s mouth is covered with aluminum.
……………………….……………….Thank You Sir……………………………………………………..

54. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta

55. Balochistan University Of Information Technology, Engineering and
Management Sciences, Quetta