Subject : General Science Teacher: Mr Ehtisham Ul Haq Class: BS EDUCATION Semester: 2nd (Spring(2023-2027) Date Of Starting Of Semester : 4 September 2023 Date Of End Of Semester : 20 January 2024 University Of Sargodha Institute of Education These are the presentation slides that we prepare by our own research and work!

1. ASSIGNMENT
TOPIC NAME:
CURRENT ELECTRICITY
SUBMITTED TO:
SIR EHTISHAM UL HAQ
SUBMITTED BY:
KAMRAN ABDULLAH (LEADER) (ROLL NO 04)
MUZAMMAL ABBAS (ROLL NO 11)
SABEEN FATIMA (ROLL NO 24)
FARMAN SHER (ROLL NO 31)
SYED M. ALI RAZA SHAH (ROLL NO 41)
INSTITUTE OF EDUCATION
UNIVERSITY OF SARGODHA

2. STUDENT LEARNING OUTCOMES
After reading this chapter you will be able to understand and learn following topics.
 Concept of Electric Current
 Conventional Current.
 Ohm's Law.
 What is Resistance.
 Components of a Circuit,
 Alternating Current (AC) and Direct Current (DC)
 Dangers and Precautionary measures for electricity.
 Electrical Measuring Instruments.
 Analogue and digital Meters.
Electric Current
Electric current is the flow of charges due to free electrons in conductors and motion of positive and
negative ions in liquids and gases. “The amount of charge that passes though any cross section in one second
is called current”.
Written mathematically as I = Q/t
I = Current Q = Charge t = Time
SI unit of Current is ‘‘Ampere’’ and denoted by ‘‘A’’
1mA = 10 -3
A
1μ A = 10 -6
A

3. Conventional Current
Conventional current referred to simple as current. conventional current is assumed to flow from positive
terminal from negative terminal in most materials where electrons move from negative to positive terminal.
The amount of Positive Charge flowing. One direction. in is equivalent to the Same amount of charge
flowing in opposite direction.
-10C → -4C → +10C -10C ← +4C ← +10C
B A B A
Ohm's Law
The voltage across a conductor is directly proportional to the Current flowing through
It ,provided all physical Conditions and temperature remain constant. This is Called ohm's Law.
Ohm's Law Discovered by: "George Simon Ohm" in, 1826
Mathematically we Can write it as:
V ∞ I
V = RI , V = IR
I: Current V: Voltage R: Resistance

4. Resistance
The opposition to the flow of charges is called resistance. Resistance is equal to the ratio of potential
difference. It is a fundamental electrical parameter and is measured in ohms (Ω), and it is typically
represented by the symbol "R."
R = V / I
If one Volt potential difference applied across the ends of a conductor gives rise to a current of one ampere ,
the resistance of the conductor is one ohm.
Components of a Circuit
Electronic circuits consist of various components that work together to perform specific functions
Switch
A switch is an electrical component that can open or close a circuit, allowing or interrupting the flow of
electric current. It serves as a control element to turn devices on or off. There are various types of switches,
including toggle switches, push-button switches, rotary switches, and more, each with specific applications.
Resistor
A resistor is a passive component that provides a specific amount of resistance to the flow of electric
current. It is used to limit current, control voltage levels, and divide voltages in a circuit.

5. Capacitor
A capacitor is an energy storage component that stores and releases electrical energy in the form of an
electric field. It is used to filter, store, and release charge, and it can also block direct current (DC) while
allowing alternating current (AC) to pass. Capacitors come in various types, including electrolytic, ceramic,
and tantalum capacitors, each with specific characteristics and applications.
Types of capacitors and use
 Electrolytic Capacitors: Used in power supply circuits for their high capacitance and ability to
store energy.
 Ceramic Capacitors: Commonly employed for noise filtering and decoupling in electronic
circuits.
 Tantalum Capacitors: Compact and reliable, often found in compact electronic devices like
smartphones.
Transformers
Transformers are devices used in electrical circuits to change the voltage of electricity. They can make
voltage higher (step up) or lower (step down) while keeping the power nearly the same. This is crucial for
transmitting electricity efficiently and safely over long distances and for using different voltage levels in
various devices.

6.  Step Up Transformer: Increases voltage, with more turns on the secondary coil than the primary.
Used in power transmission to reduce energy loss over long distances.
A step-up transformer increases voltage.
For example, if you have a 220V supply and use a step-up transformer, it can convert this to a higher
voltage, like 440V or 1100V.
This is often used in power distribution to transmit electricity efficiently over long distances with less
loss.
 Step Down Transformer: Decreases voltage, with fewer turns on the secondary coil. Used in homes
to reduce high voltage from power lines to a safe level for household appliances.
A step-down transformer decreases voltage.
For example, if you have a 220V supply and use a step-down transformer, it can convert this to a
lower voltage, like 110V or 12V.
Step-down transformers are commonly used in households to reduce the high voltage from power lines
to a safer level for appliances and lighting.
Direct current and Alternative current
Direct Current (DC):
The current which always flows in one direction is called the direct current. It has a constant voltage and
does not change direction over time. Common sources of DC include batteries and solar cells.
Alternating Current (AC):
The current which changes its direction again and again is known as alternating current . It oscillates
between positive and negative cycles, typically at a fixed frequency (e.g., 50 or 60 Hz). AC is the
standard form of electricity used for power distribution in homes and most electrical devices.

7. Uses of A.C and D.C
AC (Alternating Current):
AC powers your lights, appliances, and electrical outlets in homes and buildings. AC is used for
efficient long-distance power transmission in electrical grids. AC is commonly used in electric
motors and power generators.
DC (Direct Current):
DC is what batteries provide to power devices like smartphones, laptops, and flashlights. Most
electronic devices, including computers and digital circuits, use DC power. Electric vehicles (EVs)
often use DC for their batteries and motors.
Domestic Electric Supply
Domestic electric supply is the electricity that powers your home. It comes from power plants and is
distributed through power lines to your house. In many places, the electricity is 220V. It's the power that
comes into your home. Your devices use this power to work.
Circuit Wiring
Circuit wiring is like the "path" for electricity in your home. It consists of wires that connect all your
electrical devices, lights, and outlets. The earth wire is a safety wire that provides a safe path for
electricity to go into the ground if there's a problem, like a short circuit. It keeps you safe. The
neutral wire carries electricity back to the source (like the power plant). The live wire brings
electricity into your home. It's the one you turn on and off with switches.

8. Fuses and Switches:
Fuses are safety devices designed to protect electrical circuits from excessive current (overload) and
prevent electrical fires. They consist of a wire or strip of material that melts when the current exceeds
a safe level, interrupting the circuit and cutting off the electricity supply. Fuses are typically one-
time-use devices; once they "blow" (melt), they need to be replaced with new ones.
Switches are control devices used to open or close an electrical circuit, allowing you to turn electrical
devices or lights on and off. They come in various types, including toggle switches, push-button
switches, and rotary switches. Switches provide a convenient way to control the flow of electricity
and use electrical appliances and lighting safely and efficiently.
Measurements of electric supply
If you want to know how much electricity have you consumed in a certain period, follow the procedure
given below. Note the reading of your meter in the beginning of the said period. At the end of that period,
note the reading again. The difference of both the readings is equal to the amount of electrical energy
consumed. The total price can be calculated by multiplying the consumed energy with the rate of units of
electricity.

9. Dangers of electric supply
Electric Shock:
Electric shock occurs when the body comes into contact with an electrical source, leading to the flow of
electricity through the body. It can cause injuries ranging from minor burns to severe harm, including
cardiac arrest and death.
Fire:
Electrical fires can result from faulty wiring, overheated circuits, or short circuits. They pose a significant
risk to property and safety, potentially leading to extensive damage and injury.
Explosion:
Explosions can occur in situations involving flammable gases or materials exposed to electrical sparks or
arcs. These explosions can lead to significant damage, fires, and life-threatening situations.
Precautionary measures for Electricity
 Ensure proper wiring and installation by qualified professionals.
 Regularly inspect and maintain electrical systems for damage and loose connections.
 Use circuit breakers and fuses to prevent overloads and short circuits.
 Properly ground electrical circuits to prevent electric shock and fires.
 Avoid overloading electrical outlets and using damaged cords and plugs.
 Pay attention to warning signs and labels on electrical equipment.
 Promote education and awareness of electrical safety in homes and workplaces.
Precautionary measures for Electricity safety first aid
 Ensure scene safety and disconnect the electrical source if possible.
 Call for emergency help if the accident is severe.
 Do not touch the victim until the area is safe.
 Perform CPR if the victim is not breathing or has no heartbeat.
 Cover burns and injuries with sterile, non-stick bandages or clean cloth and keep the victim warm.

10. Measuring instrument
Different instruments are used for the measurement of current, voltage and resistance. Basically,
galvanometer is an instrument which detects the current. Different measuring instruments are made by
making modification in the galvanometer.
You have learnt about electric motor in the lower classes. The principle of the galvanometer is the same as
that of an electric motor. A coil of wire is placed between the opposite magnetic poles. An axil passes
through the centre of the coil. When current is passed through the coil, it turns about the axil. The springs at
the ends of the axil are tightened as the coil rotates. They stop further rotation of the coil.
As the coil rotates, a pointer fixed on the coil also deflects along a circular scale . The more the current the
larger is the deflection. A galvanometer attains full scale deflection only with a few milliampere current.
That is why a galvanometer is not used to measure the exact amount of current, but it is used only to detect
the current.
Ammeter: An ammeter is an instrument used to measure electric current in a circuit. It functions by being
placed in series with the circuit, allowing the current to flow through it. The ammeter provides a reading in
amperes (A), indicating the amount of current passing through the circuit, which is crucial for monitoring
and maintaining the proper functioning of electrical systems.
Voltmeter: A voltmeter is designed to measure electrical voltage or potential difference across components
in a circuit. It operates by being connected in parallel with the part of the circuit where voltage is to be
measured. Voltmeters have high internal resistance to minimize the impact on the circuit they are measuring.
They provide voltage readings in volts (V), helping to assess the health and safety of electrical systems by
indicating the electrical potential at specific points in a circuit.
Multimeter: A multimeter is a versatile electrical measuring instrument that combines the functions of an
ammeter, voltmeter, and ohmmeter in one device. It measures current, voltage, and resistance in electrical
circuits. Multimeters work by selecting the appropriate measurement mode, connecting the instrument to the
circuit, and displaying the measured value digitally or analogically, making them essential tools for
diagnosing and troubleshooting electrical problems.

11. Analogue and digital meters
The meters about which you have read so far are such that you have to note the position of a pointer on the
circular scale to take the reading. As the scale is continuous, so every reading is possible in the scale. Such
meters are called analogue meters. A meter shown is an analogue meter.
There is also an electronic meter for measuring current potential difference and resistance. That is called the
digital meter. It also performs all the functions of an AVO meter. But the difference is that in a digital multi-
meter, the reading is displayed in the form of digits that can be read easily. Error is possible by the human
eye while looking at the position of the pointer on the scale of an analogue meter. On the other hand, this
error is not possible in the digital meter because of its display in digits.
THE END
Thank You For Reading