1.
Ohm’s Law
When its dark, you just press turn on the light switch. It is quiet
interesting to know how the room gets lighted in a blink of an eye.

2.
When electricity flows through the circuit, it experiences
hindrance. This hindrance is also known as the resistance. In a circuit,
the wires and connections have internal resistances that hinder (resist)
the flow of charges.
If the circuit is not complete, there will be no current flowing
through it.
Ohm’s Law states that voltage is directly proportional to current
under constant resistance.

3.
Mathematically, this is written as:
V = IR
Where
V = Voltage in V
I = current in A
R = resistance in Ω
Consider the following sample problems to apply the formula of Ohm’s law.

4.
Example:
What is the voltage of a circuit if the current passing through it is 1.50
A and the total resistance is 23 Ω?
Solution:
I = 1.50 A
R = 23 Ω
V = ?
V = IR
V = (1.50 A) (23 Ω)
V = 34.5 V
So, the voltage of the circuit is 34.5 V.

5.
Georg Simon Ohm formulated Ohm’s law. He found the
relationship among voltage, resistance and current and expressed it as
V = IR. Most materials follow Ohm’s law, but there are few materials
that do not abide by this law. These are called non-ohmic materials.

6.
VOLTAGE
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Voltage, which is also known as
electromotive force or potential
difference is the electric pressure
that causes current to flow. The
voltage level is similar to the
pressure of water at different
heights.

7.
VOLTAGE
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The symbol for voltage is V.

8.
RESISTANCE
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Resistance is the opposition a
material offers to current. The
symbol for resistance is R.

9.
RESISTANCE
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All materials offer some resistance to
current, but the amount of resistance
differs from each other. There are
high-resistance and low-resistance
materials. More energy is required to
move electrons through high-
resistance materials.

10.
ELECTRICITY
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11.
Problem-Solving:
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1.) How much current flows
through a lamp with
resistance 90 Ω when it is
connected to a 220-V
outlet?

12.
Problem-Solving:
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2.) How much current flows
through a lamp with
resistance 50 Ω when it is
connected to a 300-V
outlet?

13.
Problem-Solving:
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3.) How much current flows
through a lamp with
resistance 36 Ω when it is
connected to a 720-V
outlet?

14.
Problem-Solving:
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4.) How much current flows
through a lamp with
resistance 45 Ω when it is
connected to a 2756-V
outlet?

15.
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18.
SAFETY WITH CIRCUIT
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• Circuit breaker - is like an automatic
switch that turns of the circuit when
there is overloading of current (which
can cause fire).
• Fuse - This is sometimes referred to as
the sacrificial device. This is because
fuse melts when there is overloading of
current. This prevents damage to the
circuit.

19.
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20.
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21.
Performance Task
Direction: You and your classmates are tasked to decorate your
classroom using Christmas lights. After that discuss how Ohm’s law
works with your performance task. Your output will be evaluated using
the following criteria's, creativity 10 points, uniqueness 10 points, class
participation 10 points.