Profile
Settings
Refer your friends
Sign out
If the temperature of the object remains constant, Ohm’s rule states that the current I in a resistor is proportional to the potential difference V across it. In
It claims to be in equation form.
R=V/I
where R is the device’s resistance and P is the proportionality constant.
A straight line is created by charting V vs I, with a slope equal to the value of the resistor R at constant temperature.
The electric field E is directly proportional to the current density J at any point inside the conductor:
(VECTOR OF E) =ρ ×(VECTOR OF J)
where ρ is the conductor’s resistivity, which remains constant at a fixed temperature. Because it is impossible to directly quantify the current density and electric field, it is preferable to reformulate the equation (1) in terms of measurable physical quantities such as current and potential difference.
If the conductor’s cross section area is A, then:
J=I/A
and the potential difference V between the conductor’s ends is calculated using the equation
V= (vector of E)×(vector of L)
where L is length of the conductor, then equation (1) becomes
VL=ρIA
WHICH CAN ALSO BE WRITTEN AS
R=VI
This equation is known as Ohm’s law, which states that resistance is the constant proportionality connecting to the potential difference to the current.
Required Materials For conducting the experiment
1. Eliminator of batteries
2. Ammeter / Voltmeter
3. Rheostat
4. Key to a one-way plug
5. Resistor
6. Wire connections
FACTOR WHICH AFFECT RESISTANCE
The conductor’s length (R l)
The conductor’s cross-sectional area (R 1/A)
The material’s nature
CIRCUIT DIAGRAM
PROCEDURE:
As shown in the circuit diagram, connect the devices.
Take note of the ammeter and voltmeter’s lowest counts.
Take note of the voltmeter and ammeter readings. Remove the plug or turn the battery eliminator off for a few moments.
Variate the sliding terminal of the rheostat to repeat steps 3 and 4 for different current values.
R = V/I is the formula for calculating resistance.
Plot a graph with I on the y-axis and V on the x-axis, or vice versa.
OBSERVE AND WRITE
Voltmeter and ammeter least count and range
Readings of voltmeter and ammeter
Calculate using the formula for finding resistance
GRAPH
PRECAUTIONS
As connecting cables, thick copper wires should be utilised, and their insulation should be stripped using sandpaper.
The connections must be secure.
The voltmeter and the resistor should be linked in parallel.
The current should be passed for a brief duration to avoid overheating the circuit.
SOME KEY ASPECTS:
A resistor, a battery pack, an ammeter, and a voltmeter are commonly used in physics labs to investigate Ohm’s law. An ammeter is a device that measures current at a specific place. A voltmeter is a device with probes that can be touched to two points on a circuit to assess the difference in electric potential between them. The electric potential differential across the external circuit can be changed by changing the number of cells in the battery pack. You’ll need to know the current flowing through the resistor as well as the resistor’s value to figure out the potential difference. When you multiply the two, you get voltage or potential.
Every resistor lowers a specific amount of voltage proportional to its resistance when linked to a voltage source or any supply source.
“Drops” denotes a reduction in voltage following the resistor.
A voltmeter connected in parallel (across) the resistor can be used to measure the reduction in voltage.
The voltage across the resistor is now visible in the voltmeter; however, if you check the voltage after the resistor terminal by connecting a voltmeter across the terminal after resistance and ground, you will see a voltage that is lower than the supply voltage; this is known as the potential difference.
VISUAL EXAMPLE TO UNDERSTAND
Allow me to attempt to visualise it for you. Assume a stream or river is flowing downhill. The slope has a direct relationship with the speed of the water. Consider placing a number of rocks in the water’s route. The water slows down when it comes into contact with three rocks.
There is current in the water. The potential difference is the degree of slope. The potential decline is comparable to a decrease in water speed.
CONCLUSION
The R-value is the same and consistent for all three readings.
A resistor’s resistance is defined as the ratio of potential difference V to current I.
Ohm’s law is confirmed using the graph between V and I, as the plot is a straight line.
A circuit’s current is proportional to the electric potential difference impressed at its ends and inversely proportional to the external circuit’s total resistance. The current is proportional to the battery voltage (electric potential difference).
Ohm’s law may be tested experimentally, and we can use it to determine the value of an unknown resistance and to test series and parallel resistor combinations.
