A magnetic dipole experiences a torque of 80sqrt3mathrm~N~m when placed in uniform magnetic field in such a way that dipole moment makes angle of 60^circ with magnetic field. The potential energy of the dipole is :

Solution & Explanation

### Related Formula The torque vectau experienced by a magnetic dipole in a uniform magnetic field vecB is given by: vectau = vecM times vecB Rightarrow tau = MB sintheta The potential energy U of the dipole is given by: U = -vecM cdot vecB = -MB costheta ### Core Logic Given parameters: - Torque tau = 80sqrt3mathrm~N~m - Angle theta = 60^circ ### Step 1: Calculate the value of MB Substitute the given values into the torque formula: 80sqrt3 = MB sin(60^circ) 80sqrt3 = MB left(fracsqrt32right) MB = 160mathrm~J ### Step 2: Calculate Potential Energy Using the potential energy expression: U = -MB cos(60^circ) U = -160 times frac12 = -80mathrm~J ### Pattern Recognition A standard dipole problem checking the relation between torque and potential energy. Note that torque goes with the sine of the angle, whereas potential energy goes with the negative cosine. Dividing torque by potential energy gives -tantheta. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Magnetism and Matter

Reference Study Guides

More Magnetism and Matter Previous-Year Questions — Page 2

Q55 jee_main_2024_29_jan_morning Magnetic Dipole
The magnetic potential due to a magnetic dipole at a point on its axis situated at a distance of 20 mathrm~cm from its center is 1.5 times 10^-5 mathrm~T cdot m. The magnetic moment of the dipole is ________ mathrmA cdot m^2. left(text Given: fracmu_04 pi = 10^-7 mathrm~T cdot m cdot A^-1right)$
Numerical Answer. Answer: 6 to 6

Solution

### Related Formula The magnetic potential (V) at an axial location at distance r from the center of a magnetic dipole is given by: V = fracmu_04pi fracMr^2 where M represents the magnetic moment. ### Core Logic Given values: V = 1.5 times 10^-5 mathrm~T cdot m r = 20 mathrm~cm = 0.2 mathrm~m fracmu_04pi = 10^-7 mathrm~T cdot m cdot A^-1 ### Step 1: Set up the Formula Substituting values into the axial expression: 1.5 times 10^-5 = 10^-7 times fracM(0.2)^2 1.5 times 10^-5 = 10^-7 times fracM0.04 ### Step 2: Isolate and Compute M M = frac1.5 times 10^-5 times 0.0410^-7 M = frac0.06 times 10^-510^-7 = 0.06 times 10^2 = 6 mathrm~A cdot m^2 Therefore, the magnetic moment of the dipole is 6 \mathrm{~A \cdot m^2}. ### Pattern Recognition Axial potential fields scale inversely with the square of distance (V \propto \frac{1}{r^2}$), analogous to electrostatic dipole potentials. Ensure the distance is converted directly to meters before squaring. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Magnetism and Matter

More Magnetism and Matter Questions — jee_main_2025_03_april_evening

Practice all Magnetism and Matter previous-year questions →

Rankbit System
JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)