All Courses
Explore Courses UPSC Exam UPSC Test Series Free Notes EduRev Infinity Get the App Login Join for Free
Sign in Open App
Defence Exam  >  Defence Questions  >  The resistance of a wire of length / and area... Start Learning for Free
SaveJoin the Discussion on the App
The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:
  • a)
    2x ohm
  • b)
    0.5 x ohm
  • c)
    4x ohm
  • d)
    6x ohm
Correct answer is option 'C'. Can you explain this answer?
FREE This question is part of
Download PDF Attempt Test
Download PDF Attempt this Test
Verified Answer
The resistance of a wire of length / and area of cross-section a is x ...
Resistance is directly proportional to length(l)
r ∝ 1 5 r ∝ 1/a
wire is stretched to double its length the resistance will become
r ∝ 1, r ∝ 1/a/2 Combining these two r ∝ 41/a 
View all questions of this test
Most Upvoted Answer
The resistance of a wire of length / and area of cross-section a is x ...
Resistance of a Wire

The resistance of a wire is determined by its length, cross-sectional area, and the material it is made of. According to Ohm's law, the resistance (R) of a wire is given by the formula R = ρ * (L / A), where ρ is the resistivity of the material, L is the length of the wire, and A is the cross-sectional area.

Given Information

In the given question, we are told that the resistance of a wire of length L and cross-sectional area A is x ohms. Let's denote this as R1 = x ohms.

Effect of Stretching the Wire

When the wire is stretched to double its length, its new length becomes 2L. We need to find the new resistance of the wire, which we'll denote as R2.

Using Ohm's Law

Let's use Ohm's law to find the new resistance of the wire.

R2 = ρ * (2L / A)

Since the resistivity and cross-sectional area of the wire remain the same, we can simplify the equation as follows:

R2 = 2 * ρ * (L / A)

Comparing R2 and R1

We know that R1 = x ohms, so we can compare R2 and R1 to determine the relationship between them.

R2 / R1 = (2 * ρ * (L / A)) / x

Simplifying further:

R2 / R1 = 2 * (L / A) * (ρ / x)

Since (L / A) and (ρ / x) are constant values for the wire, we can write:

R2 / R1 = constant

This means that the ratio of R2 to R1 remains constant. Therefore, the new resistance of the wire (R2) is directly proportional to the initial resistance (R1).

Conclusion

Since the initial resistance (R1) is x ohms, the new resistance (R2) will be 2x ohms when the wire is stretched to double its length.

Therefore, the correct answer is option C) 4x ohms.
< Previous Question Next Question >
Explore Courses for Defence exam

Similar Defence Doubts

Read the following passage carefully and answer the questions given below it.Some gene mutations produce characteristics so undesirable that it is difficult to imagine any reasonable change in environmental conditions that would make them beneficial. There are mutations that lead to the nondevelopment of hands and feet, to the production of blood that will not clot, to serious malformations of essential organs, and so on. Any mutation that brings about death before the gene producing it can be passed on to another generation is a lethal mutation. A gene governing a lethal characteristic may be dominant. Under such conditions, the lethal gene is removed in the same generation in which it is formed. The lethal gene may, on the other hand, be recessive. Its effect is then not evident if the gene it is paired with is normal. The normal gene carries on for both. When this is the case, the lethal gene will remain in existence and will, every once in a while, make itself evident. These undesirable genes may be passed along for generations, even if dominant, before natural selection culls them out. The more seriously undesirable they are, the more quickly they are removed, but even outright lethal genes will be included among the chromosomes from generation to generation provided they are recessive. These deleterious genes make up the genetic load. The gene pool is necessary for the flexibility that will allow a species to survive and evolve over the eons and the genetic load is the price that must be paid for that. The size of a genetic load depends on two factors: The rate at which a deleterious gene is produced through mutation, and the rate at which it is removed by natural selection. When the rate of removal equals the rate of production, a condition of genetic equilibrium is reached and the level of occurrence of that gene then remains stable over the generations.Q.According to the passage, when does the dominant deleterious gene become lethal?

The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:a)2x ohmb)0.5 x ohmc)4x ohmd)6x ohmCorrect answer is option 'C'. Can you explain this answer?
Question Description
The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:a)2x ohmb)0.5 x ohmc)4x ohmd)6x ohmCorrect answer is option 'C'. Can you explain this answer? for Defence 2024 is part of Defence preparation. The Question and answers have been prepared according to the Defence exam syllabus. Information about The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:a)2x ohmb)0.5 x ohmc)4x ohmd)6x ohmCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Defence 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:a)2x ohmb)0.5 x ohmc)4x ohmd)6x ohmCorrect answer is option 'C'. Can you explain this answer?.
Solutions for The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:a)2x ohmb)0.5 x ohmc)4x ohmd)6x ohmCorrect answer is option 'C'. Can you explain this answer? in English & in Hindi are available as part of our courses for Defence. Download more important topics, notes, lectures and mock test series for Defence Exam by signing up for free.
Here you can find the meaning of The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:a)2x ohmb)0.5 x ohmc)4x ohmd)6x ohmCorrect answer is option 'C'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:a)2x ohmb)0.5 x ohmc)4x ohmd)6x ohmCorrect answer is option 'C'. Can you explain this answer?, a detailed solution for The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:a)2x ohmb)0.5 x ohmc)4x ohmd)6x ohmCorrect answer is option 'C'. Can you explain this answer? has been provided alongside types of The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:a)2x ohmb)0.5 x ohmc)4x ohmd)6x ohmCorrect answer is option 'C'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice The resistance of a wire of length / and area of cross-section a is x ohm. If the wire is stretched to double its length, its resistance would become:a)2x ohmb)0.5 x ohmc)4x ohmd)6x ohmCorrect answer is option 'C'. Can you explain this answer? tests, examples and also practice Defence tests.
Explore Courses for Defence exam
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev
Get App
© EduRev
Education Revolution
Follow Us
Signup to see your scores go up within 7 days!
Access 1000+ FREE Docs, Videos and Tests
Takes less than 10 seconds to signup