Mada za sehemu hiiElectric EnergyMada 5
A simple electric circuit will be used to verify Ohm's Law. A simple electric circuit is made up of a dry cell, a switch, a bulb used as a resistor and a wire connecting them as shown.
In verifying Ohm's Law, it is important to understand a simple electric circuit and how it works. The dry cell as a source of electric current produces an electromotive force (e.m.f) which is also known as voltage (V). The voltage across a resistor is the potential difference between its two ends. The electric current flows from the source as indicated by the arrows, through a resistor and switch in a closed circuit. The resistor in a circuit produces resistance to flow of electric current. An ammeter measures electric current in amperes (A) and a voltmeter measures potential difference in volts (V).
The voltage (V), electric current (I) and resistance (R) in an electric circuit have the following relationships:
- When the resistance in a circuit is constant, increase in voltage increases the current and when the voltage decreases the current also decreases.
- When the voltage in a circuit is kept constant, decrease in resistance increases the current and when the resistance increases, the current decreases.
Ohm's Law states that, the current through a resistor is directly proportional to the voltage across its two ends.
If a conductor has a resistance (R), and current (I) flowing through it, then the voltage (V) across the conductor is given by
V = I × R
V = I × R
Where:
- V is the voltage (in volts)
- I is the current (in amperes)
- R is the resistance (in ohms)
I = V / R
Where:
- I is the current (in amperes)
- V is the voltage (in volts)
- R is the resistance (in ohms)
R = V / I
Where:
- R is the resistance (in ohms)
- V is the voltage (in volts)
- I is the current (in amperes)
Ohm's Law plays a key role in the design and manufacturing of various electric appliances. It is used in devices such as:
- Mobile Phones
- Computers
- Televisions
- Electric Irons
- Electric Kettles
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