2. Sample Papers
  3. NEET

NEET Sample Paper NEET Sample Test Paper-10

  • question_answer
    A length of wire carries a steady current. It is bent first to form circular coil of one turn. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre caused by the same current is:

    A)  a quarter of its first value

    B)  unaltered

    C)  fourtimes of its first value

    D)  half of its first value

    Correct Answer: C

    Solution :

    As, magnetic field due to a circular coil axis centre is given by \[{{B}_{0}}=\frac{{{\mu }_{0}}nI}{2r}\] \[\frac{{{B}_{1}}}{{{B}_{2}}}=\frac{{{n}_{1}}}{{{n}_{2}}}\left( \frac{{{r}_{2}}}{{{n}_{1}}} \right)\] Where,   \[{{n}_{1}}=1,\,\,{{n}_{2}}=2,\,\,{{r}_{2}}=\frac{{{r}_{1}}}{2}\] Then,     \[\frac{{{B}_{2}}}{{{B}_{1}}}=\frac{4}{1}\]   \[\Rightarrow \] \[{{B}_{2}}=4{{B}_{1}}\]    


You need to login to perform this action.
You will be redirected in 3 sec spinner