A uniform wire of resistance 3 ohm is folded in such a way that it forms an equilateral triangle, then what is it's resistance across the ends of any two vertices?
Correct answer: C. 2/3 ohm
- A. 2 ohm
- B. 3 ohm
- C. 2/3 ohm
- D. 3/2 ohm
Explanation
Since we have a uniform wire, therefore the resistance of each side of the triangle will be equal as the length of each is also equal. Three sides mean that each side will have resistance 3 ohm/3 = 1 ohm. If the resistance is to be measured across A and B, then it is clear that two of the three sides are connected in series: R = 1 + 1 = 2 ohms. And this combination is connected in parallel with the third side: 1/R = 1/1 + 1/2 = 3/2 R = 2/3 ohm.
This question appeared on the NUMS 2019 (cancelled sitting) paper, which you can sit online with every answer explained.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Resistance and Resistivity
Resistance measures opposition to current in a conductor and follows R = V/I for an ohmic conductor, while resistivity is an intrinsic property of the material. Questions use R = ρL/A, examine effects of length, cross-sectional area and temperature, and distinguish resistance, resistivity, conductance and conductivity.
Practise Current Electricity
1,052 free Current Electricity MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Resistance and Resistivity questions
The dimension of elastic modulus is ___________________ ?
A wire having very high value of conductance is said to be____________________?
Resistance of an ideal insulator is __________________?
A wire of resistance 'R' is stretched till its radius is half of the original value. The 2R resistance of stretched wire is:
'A wire of uniform cross-sectional area 'A' and length 'L' is cut into two equal parts. The resistance of each part becomes.
Slope of I-V graph of a resistor is numerically equal to: