2. Solved Papers
  3. CET Karnataka Engineering

CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2003

  • question_answer
    A wire in the form of a circular loop of one turn carrying a current produces a magnetic field B at the centre. If the same wire is looped into a coil of two turns and carries the same current, the new value of magnetic induction at the centre is:

    A)  3 B                        

    B)  5 B

    C)  4 B                        

    D)  2 B

    Correct Answer: C

    Solution :

    Magnetic field at the centre of a current carrying loop is given by                 \[B=\frac{{{\mu }_{0}}\,ni}{2r}\] Here: \[n=\] no. of turns in loop \[i=\] current, \[{{r}_{1}}=\] radius of loop, \[{{r}_{1}}=r\]                 For \[n=1\] turn                 \[B=\frac{{{\mu }_{0}}i}{2{{r}_{1}}}\]                                      ... (1) When \[n=2\] turns and radius \[{{r}_{2}}=\frac{r}{2},\,\,{{i}_{2}}=i\] or            \[{{B}_{2}}=\frac{2{{\mu }_{0}}i\times 2}{2r}\]                                   ?. (2) Now, from eqn. (1) and (2)                 \[\frac{{{B}_{2}}}{B}=4\] Hence, \[{{B}_{2}}=4B\]


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