SS1: PHYSICS – 3RD TERM

Production of Electric Current  Week 16 Topics1 Quiz

Electric Current  Week 25 Topics1 Quiz

Electrical Resistance of a Conductor  Week 35 Topics1 Quiz

Particulate Nature of Matter  Week 45 Topics1 Quiz

Crystalline and Noncrystalline Substances  Week 53 Topics1 Quiz

Elastic Properties of Solids  Week 6 & 74 Topics1 Quiz

Fluids at Rest & in Motion  Week 8 & 96 Topics1 Quiz

Solar Collector3 Topics1 Quiz
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Ohm’s Law
A German scientist Georg Simon Ohm investigated the relationship between voltage or potential difference and current flowing along a metallic conductor. His finding is known as Ohm’s law which is stated as follows;
The current flowing along a metallic conductor at constant temperature is directly proportional to the potential difference across its end provided other physical conditions remain constant.
If V represents the potential difference in volts, I represent the current flowing in amperes, then
\( \scriptsize V \propto I \)V = IR
R = \( \frac {V}{I} = \frac {Potential\; difference}{current}\)
R is a constant of proportionality known as resistance of a conductor. It depends on the nature of the conductor
∴ V = IR
I = \(\frac{V}{R}\)
The unit of resistance is Ohm (Ω).
Ohm is defined as the resistance of a conductor when a potential difference or a voltage of one volt is applied across the conductor causes a current of one ampere to flow through the conductor.
Limitations of Ohm’s Law: Ohm’s law holds for metals and certain materials, but some do not obey Ohm’s law. These materials include diodes, transistors, rectifiers, semiconductors, rare gas, and acids.
Let’s apply ohms law in the following examples;
Example 1
Calculate the current produced when a 350volt cell is connected across a 12 ohms resistor.
Solution:
Values in the question:
Voltage V = 350 volt, Resistance R = 5 ohms, current I = ?
Formula:
Voltage V = IR
Substitute the values given into the equation
350 = I x 5
Make current the subject of the formula:
current I = \( \frac{350}{5}\) .
Current I = 70 Amperes
Now go ahead and solve this on your own.
Exercise 1
Determine the value of resistance that will cause a voltage of 125 Volt to generate 2.5 Amperes of Current.
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