What is the main difference between paramagnetic and ferromagnetic substances?
What is the main difference between paramagnetic and ferromagnetic substances?
Show Hint
Solution and Explanation
- Paramagnetic substances have unpaired electrons and exhibit weak magnetic moments.
- Ferromagnetic substances have domains aligned in a magnetic field and show strong magnetic behavior even when the external field is removed.
Top Questions on Electromagnetic Field (EMF)
A proton is moving undeflected in a region of crossed electric and magnetic fields at a constant speed of \( 2 \times 10^5 \, \text{m/s} \). When the electric field is switched off, the proton moves along a circular path of radius 2 cm. The magnitude of electric field is \( x \times 10^4 \, \text{N/C} \). The value of \( x \) is \(\_\_\_\_\_\). (Take the mass of the proton as \( 1.6 \times 10^{-27} \, \text{kg} \)).
- JEE Main - 2025
- Physics
- Electromagnetic Field (EMF)
In the first configuration (1) as shown in the figure, four identical charges \( q_0 \) are kept at the corners A, B, C and D of square of side length \( a \). In the second configuration (2), the same charges are shifted to mid points C, E, H, and F of the square. If \( K = \frac{1}{4\pi \epsilon_0} \), the difference between the potential energies of configuration (2) and (1) is given by:
- JEE Main - 2025
- Physics
- Electromagnetic Field (EMF)
- The fractional compression \( \frac{\Delta V}{V} \) of water at the depth of 2.5 km below the sea level is:
- JEE Main - 2025
- Physics
- Electromagnetic Field (EMF)
- Due to the presence of an em-wave whose electric component is given by \( E = 100 \sin(\omega t - kx) \, \text{N/C} \), a cylinder of length 200 cm holds a certain amount of em-energy inside it. If another cylinder of the same length but half the diameter of the previous one holds the same amount of em-energy, the magnitude of the electric field of the corresponding em-wave should be modified as:
- JEE Main - 2025
- Physics
- Electromagnetic Field (EMF)
Show that the circumference of the orbit of an electron revolving in the \( n \)-th orbit is equal to \( n\lambda \) with the help of Bohr's quantum theory. Also, show the emission and absorption spectral lines between energy levels \( n = 1 \) and \( n = 3 \) of hydrogen atom.
- UP Board XII - 2024
- Physics
- Electromagnetic Field (EMF)
Questions Asked in UP Board XII exam
- What is meant by the transformation ratio of a transformer? In a step-down transformer, the transmission line voltage of 2200 volt is changed to 220 volt. Number of turns in the primary coil is 5000. The efficiency of the transformer is 90 percent and output power is 8kW.
- UP Board XII - 2024
- KCL/ KVL in AC Circuits
Two parallel plate capacitors of capacitances \( C \) and \( 2C \) are joined with a battery of voltage difference \( V \) as shown in the figure. If the battery is removed and the space between the plates of the capacitor of capacitance \( C \) is completely filled with a material of dielectric constant \( K \), then find out:
- i) Total capacitance of the combination
- ii) Final voltage difference across the combination
- iii) Total energy stored in the combination.
- UP Board XII - 2024
- Refractive index
Differentiate between interference and diffraction of light. Explain qualitatively the diffraction phenomenon of light by a single slit. Light of 6000 Ã… wavelength is incident normally on a single slit of width \( 3 \times 10^{-4} \, \text{cm} \). Find out the angular width of the central maxima.
- UP Board XII - 2024
- Energy bands
What do you mean by the current sensitivity of a moving coil galvanometer? Resistance of a galvanometer is \( 50 \, \Omega \) and for full-scale deflection, the current is \( 0.05 \, \mathrm{A} \). What would be the required length of a wire to convert it into an ammeter of 5 A range? (Area of cross-section of wire = \( 2.7 \times 10^{-6} \, \mathrm{m^2} \), specific resistance of the wire material = \( 5.0 \times 10^{-7} \, \Omega \cdot \mathrm{m} \))
- UP Board XII - 2024
- The Traveling Electromagnetic Wave
Obtain the formula for the internal resistance of a cell in terms of \( E \), \( V \), and \( R \), where \( E \), \( V \), and \( R \) are the electromotive force of the cell, potential difference across the external resistance, and external resistance, respectively.
- UP Board XII - 2024
- Refraction And Reflection Of Plane Waves Using Huygens Principle