Electromagnetic Induction & AC · JEE Main previous year questions

2020 3 questions

1. Q452020 · 2 Sept 2020 · Shift 1

   Magnetic materials used for making permanent magnets (P) and magnets in a transformer (T) have different properties of the following, which property best matches for the type of magnet required?

   1. A.T : Large retentivity, small coercivity
   2. B.P : Large retentivity, large coercivity
   3. C.P : Small retentivity, large coercivity
   4. D.T : Large retentivity, large coercivity
   Show answer

   Answer: B

2. Q342020 · 2 Sept 2020 · Shift 2

   An inductance coil has an impedance of $100\Omega$. When an AC signal of frequency 1000 Hz is applied to the coil, the applied voltage leads the current by $45^{\circ }$. The self-inductance of the coil is

   1. A.$6.7\times 10^{-7}\mathrm{H}$
   2. B.$1.1\times 10^{-1}\mathrm{H}$
   3. C.$5.5\times 10^{-5}\mathrm{H}$
   4. D.$1.1\times 10^{-2}\mathrm{H}$
   Show answer

   Answer: D

3. Q462020 · 9 Jan 2020 · Shift 1· Numerical answer

   In a fluorescent lamp choke (a small transformer) 100 V of reverse voltage is produced when the choke current changes uniformly from 0.25 A to 0 in a duration of 0.025 ms. The self-inductance of the choke (in mH) is estimated to be ________.

   Show answer

   Answer: 10