ohms law and limites
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In Ohm's law the resistance is taken as constant. But there are many practical examples where the resistance of the element through which current flows, is not constant it varies with applied voltage. This type of elements will not obey Ohm's law perfectly. Ohm's law also is not applicable to the unilateral elements because they behave differently when the direction of current changes. For example, we can consider a diode whose current voltage relationship is totally different in the case of forward biased and reverse biased condition. Moreover Ohm's law cannot be applied to the non-linear elements like powdered carbon, thyrite, electric arc etc.
sathya111:
ohms law gives the relationship bw the applied potential diff across the conductor and the resuling current is zero
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Answer:
OHM'S LAW
According to Ohm's law : At constant temperature the current flowing through a conductor is directly proportional to the potential difference across it's ends. If 'I' is the current flowing through a conductor and 'V' is the potential difference across it's ends then according to Ohm's law :
'I' is directly proportional to 'V'.
(At constant temperature)
So, 'V'is directly proportional to 'I'.
Therefore, V = R × I
where 'R' is a constant called "resistance" of the conductor. The value of this constant depends on the nature, length, area of cross section and temperature of the conductor.
The above equation can be written as :
[ V / I = R ]
where,
V = Potential difference
I = Current
R = Resistance (constant)
The above equation can be written in words as :
[ Potential difference / Current = Resistance ]
The ratio of potential difference applied between the ends of a conductor and the current flowing through it is a constant quantity is called resistance.
If you find the Resistance, use this formula. By using the formula of Ohm's law we can create a formula to find resistance.
[ V / I = R ]
•°• R = V / I
Here,
* Resistance is directly proportional to potential difference.
* Resistance is inversely proportional to current.
If you find the Current, use this formula. By using the formula of Ohm's law we can create a formula to find current.
[ V / I = R ]
•°• I = V / R
Here,
* Current is directly proportional to potential difference.
* Current is inversely proportional to resistance.
If you find the Potential difference, use this formula. By using the formula of Ohm's law we can create a formula to find potential difference.
[ V / I = R ]
•°• V = IR
Here,
* Potential difference is directly proportional to current.
* Potential difference is directly proportional to resistance.
OHM'S LAW
According to Ohm's law : At constant temperature the current flowing through a conductor is directly proportional to the potential difference across it's ends. If 'I' is the current flowing through a conductor and 'V' is the potential difference across it's ends then according to Ohm's law :
'I' is directly proportional to 'V'.
(At constant temperature)
So, 'V'is directly proportional to 'I'.
Therefore, V = R × I
where 'R' is a constant called "resistance" of the conductor. The value of this constant depends on the nature, length, area of cross section and temperature of the conductor.
The above equation can be written as :
[ V / I = R ]
where,
V = Potential difference
I = Current
R = Resistance (constant)
The above equation can be written in words as :
[ Potential difference / Current = Resistance ]
The ratio of potential difference applied between the ends of a conductor and the current flowing through it is a constant quantity is called resistance.
If you find the Resistance, use this formula. By using the formula of Ohm's law we can create a formula to find resistance.
[ V / I = R ]
•°• R = V / I
Here,
* Resistance is directly proportional to potential difference.
* Resistance is inversely proportional to current.
If you find the Current, use this formula. By using the formula of Ohm's law we can create a formula to find current.
[ V / I = R ]
•°• I = V / R
Here,
* Current is directly proportional to potential difference.
* Current is inversely proportional to resistance.
If you find the Potential difference, use this formula. By using the formula of Ohm's law we can create a formula to find potential difference.
[ V / I = R ]
•°• V = IR
Here,
* Potential difference is directly proportional to current.
* Potential difference is directly proportional to resistance.
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