Magnetic Effects of Current & Magnetism · JEE Main previous year questions

2014 2 questions

1. Q492014 · 6 Apr 2014 · Shift 1

   The coercivity of a small magnet where the ferromagnet gets demagnetized is $3\times 10^3\mathrm{A}{\mathrm{m}}^{-1}$. The current required to be passed in a solenoid of length $10\mathrm{cm}$ and number of turns $100$, so that the magnet gets demagnetized when inside the solenoid, is :

   1. A.$30\mathrm{mA}$
   2. B.$60\mathrm{mA}$
   3. C.$3\mathrm{A}$
   4. D.$6\mathrm{A}$
   Show answer

   Answer: C

2. Q572014 · 6 Apr 2014 · Shift 1

   The radiation corresponding to $3\to 2$ transition of hydrogen atom falls on a metal surface to produce photoelectrons. These electrons are made to enter a magnetic field $3\times 10^{-4}\mathrm{T}$. If the radius of the larger circular path followed by these electrons is $10.0\mathrm{mm}$, the work function of the metal is close to:

   1. A.$1.8\mathrm{eV}$
   2. B.$1.1\mathrm{eV}$
   3. C.$0.8\mathrm{eV}$
   4. D.$1.6\mathrm{eV}$
   Show answer

   Answer: B