Saved Bookmarks
| 1. |
A moving coil galvanometer experience torque=ki, where iis current. IfN coils of area Aeach and moment of inertiaI is kept in magnetic field B. (i) If for current i deflection is (pi)/2, the torsional constant of spring is (x BiNA)/(pi). Find x^2 (ii) If a charge Q is passed suddenly through the galvanometer, the maximum angle of deflection is Qsqrt((BNpiA)/(xI)). Find x^2 |
|
Answer» (i) `tau=k.theta=BiNa:.k=(2BiNa)/(pi) ` (as `theta=pi//2)` (ii) `tau=BiNA` or `int_(0)^(t) taudt=BNA int_(0)^(t)IDT, I omega =BNAQ`, or `omega=(BNAQ)/I` At maximum deflection, whole kinetic energy (rotational) will be CONVERTED into potential energy of spring. Hence `1/2 I omega^(2)=1/2 k theta_("max")^(2),` Substituting the VALUES the values we get `, theta_("max")=Qsqrt((BNpiA)/(2I))` |
|