Exams › JEE Main › Physics

Magnetic materials used for making permanent magnets (P) and magnets in a transformer (T) have different properties. Which property best matches for the type of magnet required? (1) T: Large retentivity, small coercivity (2) P: Small retentivity, large coercivity (3) T: Large retentivity, large coercivity (4) P: Large retentivity, large coercivity

1. T: Large retentivity, small coercivity
2. P: Small retentivity, large coercivity
3. T: Large retentivity, large coercivity
4. P: Large retentivity, large coercivity

Correct answer: P: Large retentivity, large coercivity

Solution

A permanent magnet (P) must retain magnetisation and resist demagnetisation, so it needs large retentivity and large coercivity. A transformer core (T) is a soft magnet needing low retentivity and low coercivity. Hence the correct match is 'P: Large retentivity, large coercivity'.

Related JEE Main Physics questions

• The SI unit Weber is used for measuring which of the following quantities?
• Two identical magnetic dipoles, each having magnetic moment 1.0 A·m², are kept 2 m apart with their axes mutually perpendicular. The magnetic field at the midpoint between them is
• A material has relative permittivity εr and relative permeability μr. For a diamagnetic substance, which pair of values is physically permissible?
• A bar magnet freely suspended in the horizontal component of Earth’s magnetic field H has a time period of 4 s. If a second magnet is placed nearby and the time period becomes 2 s, then the magnetic field produced by the second magnet is:
• Which magnetic properties should the core material possess to be suitable for an electromagnet?
• A bar magnet has a length much greater than its width and thickness. In a vibration magnetometer, its oscillation period is 2 s. The magnet is then divided lengthwise into three equal pieces, and the three pieces are stacked together so that like poles are in contact. What is the oscillation period of this arrangement?

⚔️ Practice JEE Main Physics free + battle 1v1 →