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प्रश्न
State the limitations of Ohm’s law.
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उत्तर
There are two main limitations:
(i) Temperature,
(ii) Physical condition of the conductor.
It is found that the ratio V/I is mo longer constant when the temperature is not kept constant. Generally, resistance increases with the rise in the temperature of the conductor.
Physical conditions of any conductor mainly include:
(i) Its length,
(ii) Its cross-sectional area,
(iii) The kind of material.
If there is no change in any of the above three conditions and also other condition like temperature remains constant, then Ohm’s law holds good, i.e., the ratio V/I remains constant.
संबंधित प्रश्न
If the potential difference across the ends of a conductor is 220 V and the resistance of the conductor is 44 Ω (ohm), then the current flowing through is _________.
- 0.2 A
- 0.5 A
- 2 A
- 5 A
Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
Write the formula of resistivity
Ohm's law gives a relationship between:
(a) current and resistance
(b) resistance and potential difference
(c) potential difference and electric charge
(d) current and potential difference
A resistance of 40 ohms and one of 60 ohms are arranged in series across 220 volt supply. Find the heat in joules produced by this combination of resistances in half a minute.
In an experiment of verification of Ohm’s law following observations are obtained.
|
Potential difference V (in volt) |
0.5 | 1.0 | 1.5 | 2.0 | 2.5 |
| current I (in ampere) | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 |
Draw a V-I graph and use this graph to find:
- the potential difference V when the current I is 0.5 A,
- the current I when the potential difference V is 0.75 V,
- the resistance in a circuit.
Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1 mm. Conductor B is a hollow tube of outer diameter 2 mm and inner diameter 1 mm. Find the ratio of resistance RA to RB.
The circuit depicted in the figure is employed for studying Ohm’s Law. Instead of using a standard resistor, a student opts for a glass tube filled with mercury (tube 1), connected to the circuit through two electrodes, E1 and E2. He records the readings of the ammeter and voltmeter, thereby calculating the resistance. The student repeats the experiment by substituting tube 1 with tube 2, where the same amount of mercury fills tube 2.
Neglecting internal resistance of the cell use (> or < or =) to compare:
- the resistance in both the cases.
- the voltmeter readings in both the cases.
- the specific resistance in both the cases.
