JEE Mains · Physics · STD 12 - 4. Moving charges and magnetism
N equally spaced charges each of value q , are placed on a circle of radius R . The circle rotates about its axis with an angular velocity \(\omega\) as shown in the figure. A bigger Amperian loop B encloses the whole circle where as a smaller Amperian loop A encloses a small segment. The difference between enclosed currents, \(I_A-I_B\), for the given Amperian loops is:
- A \(\frac{2 \pi}{N} q \omega\)
- B \(\frac{\mathrm{N}^2}{2 \pi} \mathrm{q} \omega\)
- C \(\frac{\mathrm{N}}{\pi} \mathrm{q} \omega\)
- D \(\frac{\mathrm{N}}{2 \pi} \mathrm{q} \omega\)
Answer & Solution
Correct Answer
(D) \(\frac{\mathrm{N}}{2 \pi} \mathrm{q} \omega\)
Step-by-step Solution
Detailed explanation
\(\begin{aligned} & I_A=\frac{N q}{\frac{2 \pi}{\omega}} \\ & I_A=\frac{N q \omega}{2 \pi}, I_B=0 \\ & I_A=I_B=\frac{N q \omega}{2 \pi}\end{aligned}\)
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
- A car of mass ' \(m\) ' moves on a banked road having radius ' \(r\) ' and banking angle \(\theta\). To avoid slipping from banked road, the maximum permissible speed of the car is \(v_0\). The coefficient of friction \(\mu\) between the wheels of the car and the banked road isJEE Mains 2025 Medium
- As shown in the figure, a metallic rod of linear density \(0.45\,kg\,m ^{-1}\) is lying horizontally on a smooth incline plane which makes an angle of \(45^{\circ}\) with the horizontal. The minimum current flowing in the rod required to keep it stationary, when \(0.15\,T\) magnetic field is acting on it in the vertical upward direction, will be \(....A\) \(\left\{\right.\) Use \(\left.g=10 m / s ^{2}\right\}\)
JEE Mains 2022 Medium - The number density of molecules of a gas depends on their distance \(r\) from the origin as, \(n\left( r \right) = {n_0}{e^{ - \alpha {r^4}}}\). Then the total number of molecules is proportional toJEE Mains 2019 Hard
- A uniform rod of length \('l'\) is pivoted at one of its ends on a vertical shaft of negligible radius When the shaft rotates at angular speed \(\omega\) the rod makes an angle \(\theta\) with it (see figure). To find \(\theta\) equate the rate of change of angular momentum (direction going into the paper ) \(\frac{ m \ell^{2}}{12} \omega^{2} \sin \theta \cos \theta\) about the centre of mass \((CM)\) to the torque provided by the horizontal and vertical forces \(F_{H}\) and \(F_{V}\) about the CM. The value of \(\theta\) is then such that:
JEE Mains 2020 Hard - In an experiment to measure the focal length ( \(f\) ) of a convex lens, the magnitude of object distance \((x)\) and the image distance \((y)\) are measured with reference to the focal point of the lens. The \(y-x\) plot is shown in figure. The focal length of the lens is _______ \(\mathrm{cm}\).
JEE Mains 2024 Hard - In an experiment to find \(emf\) of a cell using potentiometer, the length of null point for a cell of emf \(1.5\,V\) is found to be \(60\,cm\). If this cell is replaced by another cell of \(emf\; E\). the length-of null point increases by \(40\,cm\). The value of \(E\) is \(\frac{x}{10} V\). The value of \(x\) is \(............\)JEE Mains 2023 Medium
More PYQs from JEE Mains
- The length of the perpendicular from the point \((2, -1, 4)\) on the straight line, \(\frac{{x + 3}}{{10}} = \frac{{y - 2}}{{ - 7}} = \frac{z}{1}\) isJEE Mains 2019 Hard
- The mass per unit length of a uniform wire is \(0.135\, g / cm\). A transverse wave of the form \(y =-0.21 \sin ( x +30 t )\) is produced in it, where \(x\) is in meter and \(t\) is in second. Then, the expected value of tension in the wire is \(x \times 10^{-2} N\). Value of \(x\) is . (Round-off to the nearest integer)JEE Mains 2021 Easy
- Two particles \({A}\) and \({B}\) having charges \(20\, \mu {C}\) and \(-5\, \mu {C}\) respectively are held fixed with a separation of \(5\, {cm}\). At what position a third charged particle should be placed so that it does not experience a net electric force?
JEE Mains 2021 Medium - Let \(10\) vertical poles standing at equal distances on a straight line, subtend the same angle of elevation at a point \(O\) on this line and all the poles are on the same side of \(O\). If the height of the longest pole is \('h'\) and the distance of the foot of the smallest pole from \(O\) is \('a'\); then the distance between two consecutive poles, isJEE Mains 2015 Hard
- Let \(\mathrm{f}: \mathrm{R}-\left\{\frac{-1}{2}\right\} \rightarrow \mathrm{R}\) and \(\mathrm{g}: \mathrm{R}-\left\{\frac{-5}{2}\right\} \rightarrow \mathrm{R}\) be defined as \(f(x)=\frac{2 x+3}{2 x+1}\) and \(g(x)=\frac{|x|+1}{2 x+5}\). Then the domain of the function \(fog\) is :JEE Mains 2024 Hard
- If the range of the function \(f(x)=\frac{5-x}{x^2-3 x+2}\), \(x \neq 1,2\), is \((-\infty, \alpha] \cup[\beta, \infty)\), then \(\alpha^2+\beta^2\) is equal to:JEE Mains 2025 Medium