NEET · Physics · STD 12 - 4. Moving charges and magnetism
A long straight wire of radius \(a\) carries a steady current \(I.\) The current is uniformly distributed over its cross-section. The ratio of the magnetic fields \(B\) and \(B',\) at radial distances \(\frac{a}{2}\) and \(2a\) respectively, from the axis of the wire is
- A \(\frac{1}{2}\)
- B \(1\)
- C \(4\)
- D \(\;\frac{1}{4}\)
Answer & Solution
Correct Answer
(B) \(1\)
Step-by-step Solution
Detailed explanation
Magnetic field at a point inside the wire at distance \(r\left(=\frac{a}{2}\right)\) from the axis of wire is \(B=\frac{\mu_{0} I}{2 \pi a^{2}} r=\frac{\mu_{0} I}{2 \pi a^{2}} \times \frac{a}{2}=\frac{\mu_{0} I}{4 \pi a}\)
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
- Pick the wrong answer in the context with rainbowNEET 2019 Easy
- Two astronauts are floating in gravitational free space after having lost contact with their spaceship. The two willNEET 2017 Easy
- The ratio of frequencies of fundamental harmonic produced by an open pipe to that of closed pipe having the same length isNEET 2023 Easy
- A rectangular wire loop of sides 8 cm and 3 cm with a small cut, is moving out of a region of uniform magnetic field of magnitude 0.3 T directed normal to the plane of the loop. The emf developed across the cut, if the velocity of the loop is \(2 cm s ^{-1}\), in a direction normal to the shorter side of the loop, will be :NEET 2026 Easy
- A potentiometer is an accurate and versatile device to make electrical measurements of \(EMF\) because the method involvesNEET 2017 Easy
- A series LCR circuit with inductance \(10\,H\), capacitance \(10\,\mu F\), resistance \(50\,\Omega\) is connected to an ac source of voltage, \(V=200 \sin (100 t)\) volt. If the resonant frequency of the LCR circuit is \(\nu_{0}\) and the frequency of the ac source is \(v\), then:NEET 2022 Medium
More PYQs from NEET
- Given below are two statements: Statement \(I\): Mendel studied seven pairs of contrasting traits in pea plants and proposed the Laws of Inheritance Statement \(II\) : Seven characters examined by Mendel in his experiment on pea plants were seed shape and colour, flower colour, pod shape and colour, flower position and stem height In the light of the above statements, choose the correct answer from the options given below:NEET 2022 Medium
- Match the following organisms with thelr respective characteristics
Select the correct option from the following.Organisms Thelr respective characteristics (a) Pila (i) Flame cells (b) Bombyx (ii) Comb plates (c) Pleurobrachla (iii) Radula (d) Taenla (iv) Malpighlan tubules NEET 2019 Medium - \(CH _{3} CH _{2} CH = CH _{2} \frac{ B _{2} H _{6}}{ H _{2} O , H _{2} O _{2}, OH ^{-}} Z\) What is \(Z?\)NEET 2020 Medium
- \(KMnO_4\) can be prepared from \(K_2MnO_4\) as per the reaction, \(3MnO_4^{2-} + 2H_2O \rightleftharpoons 2MnO_4^- + MnO_2 + 4OH^-\) The reaction can go to completion by removing \(OH^-\) ions by addingNEET 2013 Medium
- Function of filiform apparatus is toNEET 2014 Medium
- Two parallel infinite line charges with linear charge densities \(+\lambda\; \mathrm{C} / \mathrm{m}\) and \(-\lambda\; \mathrm{C} / \mathrm{m}\) are placed at a distance of \(2 \mathrm{R}\) in free space. What is the electric field mid-way between the two line charges?NEET 2019 Medium