Ohms law.pdf

Er. Samir Raj Bhandari
Electrical Instructor
Narayani Polytechnic Institute

PRINCIPLE
OHM’S LAW 2
Saturday, January 14, 2023 Er Samir Raj Bhandrari

LEARNING OBJECTIVE
 Define Voltage, Current and Resistance.
 Define Ohms Law.
 Write the three equations of Ohms Law.
 Understand the applications of Ohms Law.
Outline the limitations of Ohms Law.
 Outline the limitations of Ohms Law.
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FACTS
 Voltage:
 Voltage is the difference in electric potential
between two points.
 The SI unit of voltage is Volts (V).
 Current:
 Current:
 The current is the rate at which electric charge
flows in a circuit at a particular point.
 The SI unit of current is Ampere (A).
 Resistance:
 The property of a material that limits current flow is
known as its resistance
 The SI unit of resistance is Ohm (Ω) 4

OHMS LAW
Georg Simon Ohm
1827,
Ohms law states that the voltage across a
conductor is directly proportional to the
current flowing through it, provided all physical
conditions and temperatures remain constant.
The galvanic circuit
investigated mathematically"
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CONTD.....
 Mathematically, this current-voltage relationship is
written as,
 In the equation, the constant of proportionality,
R, is called Resistance and has units of ohms, with
R, is called Resistance and has units of ohms, with
the symbol Ω
 The same formula can be rewritten in order to
calculate the current and resistance respectively as
follows:
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NUMERICAL PRACTICE
What is the resistance of a resistor if the current
going through it is 2A and the voltage across it
it is 10V?
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CONTD....
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ANALOGY
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OHMS LAW APPLICATIONS
 The main applications of Ohms law are:
 To determine the voltage, resistance or current
of an electric circuit.
 Ohms law maintains the desired voltage drop
across the electronic components.
across the electronic components.
 Ohms law is also used in DC ammeter and other
DC shunts to divert the current.
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LIMITATIONS OF OHMS LAW
 Following are the limitations of Ohms law:
 Ohms law is not applicable for unilateral
electrical elements like diodes and transistors
as they allow the current to flow through in one
direction only.
direction only.
 For non-linear electrical elements with
parameters like capacitance, resistance etc the
ratio of voltage and current wont be constant
with respect to time making it difficult to use
Ohms law.
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SHORT ANSWER TYPE QUESTIONS
1. What does Ohms law state?
 Ohms law states that the current through a
conductor between two points is directly
proportional to the voltage across the two points.
What is Resistance ?
2. What is Resistance ?
 The property of a material that limits current flow
is known as its resistance.
3. What is the SI unit of Current?
 The SI unit of current is Ampere (A).
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MATCHING, COMPLETION AND
MULTIPLE CHOICE TEST ITEMS
Fill in the blank with appropriate answer.
1. In SI system of measurement Current is
measured in .................
Choose the correct answer from the options given
below and write it on the blank.
below and write it on the blank.
1. The circuit element that limits flow of current is
known as ...................
a. Inductor b. Resistor
c. Voltage d. None of the above
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LONG ANSWER TYPE QUESTIONS
1. Explain Ohms law with its application and
limitations.
2. Calculate the value of resistance that is required
to limit the current to 5A if the voltage applied in
the circuit is 10V. What will happen to the current
the circuit is 10V. What will happen to the current
flow if the voltage is double and the resistance is
kept constant ? Explain the results with logical
reason.
15

HANDOUTS
3D animated Content and Explanations
 https://www.youtube.com/watch?v=AOADrgWdzrU
Theoretical Content and Explanations
 https://byjus.com/physics/ohms-law/
Study Materials and Practice Questions
Study Materials and Practice Questions
 Ohms Law.docx
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Ohms law.pdf

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