Question

"The resistance of any conductor is directly proportional to length and inversely proportional to area of cross-section of the substance" from this is concluded that _________
P: Value of resistance increases with increase in the length of conductor.
Q: Value of resistance decreases with increases in the length of conductor.
R: Value of resistance decreases with increase in the area of cross-section.
S: Value of resistance decreases with decrease in area of cross-section.

Answer 1

Hint: In this question, we will see the basics of resistance and check all the given statements. This will directly give us the required result. Further, we will also study the basics of a simple circuit, for our better understanding.

Complete answer:
As we know that, the value of resistance R is directly proportional to length of resistance. So, when we increase the length of resistance the value of resistance increases.
This shows that the statement P is correct.
Now, as the value of resistance R is also inversely proportional to area so by increasing the area the value of resistance decreases.
This shows that the statement R is also correct.

Therefore, we can conclude that the statements P and R are correct.

Additional information:
Here, as we know that the resistance is a measure of the opposition to current flow in an electrical circuit. Further, it is measured in Ohms.
Also, resistance depends upon the shape, size of a material.
We should know that in a series circuit, the output current of the first resistor flows into the input of the second resistor; so, the current is the same in each resistor whereas In a parallel circuit, all of the resistor are on connected together on one side and all the leads on the other side are connected together.
In a circuit if the resistance is constant over a range of voltage, then I = V/R, can be used to predict the behavior of the material. This involves DC current and voltage, it is the same for the resistors. Further, a material obeys Ohm's law or does not obey; the resistance of the material can be described in terms of its bulk. The resistivity, and the resistance both, is temperature dependent. Over certain ranges of temperature, this temperature dependence can be predicted from resistance.

Note:
In series connection the resistances are directly added whereas in parallel connection resistance is added inversely. Internal resistance of a circuit refers to the opposition to the flow of current offered by the cells and batteries themselves thereby, resulting in the generation of heat. Internal resistance and resistance both are measured in Ohms.