JEE Mains · Physics · STD 12 - 4. Moving charges and magnetism
A charge \(q\) is spread uniformly over an insulated loop of radius \(r\) . If it is rotated with an angular velocity \(\omega \) with respect to normal axis then the magnetic moment of the loop is
- A \(\frac{1}{2}\,\,q\omega {r^2}\)
- B \(\frac{4}{3}\,\,q\omega {r^2}\)
- C \(\frac{3}{2}\,\,q\omega {r^2}\)
- D \(q\omega {r^2}\)
Answer & Solution
Correct Answer
(A) \(\frac{1}{2}\,\,q\omega {r^2}\)
Step-by-step Solution
Detailed explanation
Magnetic moment, \(\mu \, = \,IA\, = \,\frac{{qv}}{{2\pi r}}(\pi {r^2})\) or, \(\mu \,\, = \,\,\frac{{qr\omega }}{{2\pi r}}(\pi {r^2})\, = \,\frac{1}{2}\,q{r^2}\omega \)
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
- Diameter of the objective lens of a telescope is \(250\, cm\). For light of wavelength \(600\, nm\). Coming from a distant object, the limit of resolution of the telescope is close toJEE Mains 2019 Easy
- A series \(LCR\) circuit driven by \(300\, {V}\) at a frequency of \(50 \,{Hz}\) contains a resistance \({R}=3 \,{k} \Omega\), an inductor of inductive reactance \(X_{L}=250 \,\pi \Omega\) and an unknown capacitor. The value of capacitance to maximize the average power should be : (Take \(\pi^{2}=10\) ) (in \(\mu {F}\))JEE Mains 2021 Medium
- A vehicle of mass \(200\,kg\) is moving along a levelled curved road of radius \(70\,m\) with angular velocity of \(0.2\,rad / s\). The centripetal force acting on the vehicle is \(.........\,N\)JEE Mains 2023 Medium
- A coin is placed on a disc. The coefficient of friction between the coin and the disc is \(\mu\). If the distance of the coin from the center of the disc is \(r\), the maximum angular velocity which can be given to the disc, so that the coin does not slip away, is _______.JEE Mains 2024 Hard
- A particle moves such that its position vector \(\overrightarrow{\mathrm{r}}(\mathrm{t})=\cos \omega \mathrm{t} \hat{\mathrm{i}}+\sin \omega \mathrm{t} \hat{\mathrm{j}}\) where \(\omega\) is a constant and \(t\) is time. Then which of the following statements is true for the velocity \(\overrightarrow{\mathrm{v}}(\mathrm{t})\) and acceleration \(\overrightarrow{\mathrm{a}}(\mathrm{t})\) of the particleJEE Mains 2020 Medium
- Consider a n-type semiconductor in which \(\mathrm{n}_{\mathrm{e}}\) and \(\mathrm{n}_{\mathrm{h}}\) are number of electrons and holes, respectively.
(A) Holes are minority carriers
(B) The dopant is a pentavalent atom
(C) \(\mathrm{n}_{\mathrm{e}} \mathrm{n}_{\mathrm{h}} \neq \mathrm{n}_{\mathrm{i}}^2\)
(where \(n_i\) is number of electrons or holes in semiconductor when it is intrinsic form)
(D) \(\mathrm{n}_{\mathrm{e}} \mathrm{n}_{\mathrm{h}} \geq \mathrm{n}_{\mathrm{i}}^2\)
(E) The holes are not generated due to the donors Choose the correct answer from the options given below :JEE Mains 2025 Easy
More PYQs from JEE Mains
- In a meter bridge experiment to determine the value of unknown resistance, first the resistances \(2 \Omega\) and \(3 \Omega\) are connected in the left and right gaps of the bridge and the null point is obtained at a distance \(l cm\) from the left. Now when an unknown resistance \(x \Omega\) is connected in parallel to \(3 \Omega\) resistance, the null point is shifted by 10 cm to the right of wire. The value of unknown resistance \(x\) is _________ \(\Omega\).JEE Mains 2026 Medium
- Suppose \({\tan ^{ - 1}}y = {\tan ^{ - 1}}x + {\tan ^{ - 1}}\left( {\frac{{2x}}{{1 - {x^2}}}} \right)\) , where \(\left| x \right| < \frac{1}{{\sqrt 3 }}\), then one of the value of \( y \) isJEE Mains 2015 Easy
- Unpolarized light of intensity \(I\) passes through an ideal polarizer \(A\) Another indentical polarizer \(B\) is placed behind \(A\) The intensity of light beyond \(B\) is found to be \(\frac{I}{2}\) Now another identical polarizer \(C\) is placed between \(A\) and \(B\). The intensity beyond \(B\) is now found to be \(\frac{I}{8}\) The angle between polarizer \(A\) and \(C\) is:......\(^o\)JEE Mains 2018 Medium
- Inside a uniform spherical shell \((a)\) the gravitational field is zero \((b)\) the gravitational potential is zero \((c)\) the gravitational field is same everywhere \((d)\) the gravitation potential is same everywhere \((e)\) all of the above Choose the most appropriate answer from the options given belowJEE Mains 2021 Medium
- Let \(\mathrm{A}=\left[\mathrm{a}_{i j}\right]\) be a \(2 \times 2\) matrix such that \(\mathrm{a}_{i j} \in\{0,1\}\) for all \(i\) and \(j\). Let the random variable X denote the possible values of the determinant of the matrix \(A\). Then, the variance of \(X\) is :JEE Mains 2025 Hard
- If \(y =\left(\frac{2}{\pi} x -1\right) \operatorname{cosec} x\) is the solution of the differential equation, \(\frac{d y}{d x}+p(x) y=\frac{2}{\pi} \operatorname{cosec} x, 0 < x < \frac{\pi}{2},\) then the function \(p ( x )\) is equal toJEE Mains 2020 Medium