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प्रश्न
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.
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उत्तर
- The resistance of tube 2 is less than the resistance of tube 1 because resistance depends directly on the length and inversely on the area of the resistor, and tube 2 is thicker and shorter than tube 1.
- The voltmeter reading for tube 1 is the same as the voltmeter reading for tube 2 because, according to Ohm’s law, the potential difference across a resistor depends only on the current applied, not on the resistance of the resistor.
- As the specific resistance of a resistor is independent of its dimensions but depends only on the contained material, and since here both tubes contain only mercury, the specific resistance in both cases is the same.
संबंधित प्रश्न
What is the necessary condition for a conductor to obey Ohm’s law?
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.
A metal sphere is kept on an insulting stands. A negatively charged rod is brought near it, then the sphere is earthed as shown. On removing the earthing, and taking the negatively charged rod away, what will be the nature of charge on the sphere? Give reason for your answer.
The filament of a bulb takes a current 100 mA when potential difference across it is 0.2 V. When the potential difference across it becomes 1.0 V, the current becomes 400 mA. Calculate the resistance of filament in each case and account for the difference.
What are ohmic conductors? Give one exmaple. Draw a graph showing the current-voltage relationship for an ohmic conductor.
What are non-ohmic conductors? Give one exmaple. Draw a current-voltage graph for a non-ohmic conductor.
A wire connected to a power supply of 230 V has power dissipation P1. Suppose the wire is cut into two equal pieces and connected parallel to the same power supply. In this case, power dissipation is P2. The ratio of `"P"_2/"P"_1` is
Explain the equivalent resistance of a parallel resistor network.
The unit of specific resistance is ____________.
