Question
The back $e.m.f$. induced in a coil, when current changes from $1$ ampere to zero in one milli second, is $4$ volts, the self inductance of the coil is
✓
Answer
(d) $e = - L\frac{{di}}{{dt}}$ but $e =\,4\,V$ and $\frac{{di}}{{dt}} = \frac{{0 - 1}}{{{{10}^{ - 3}}}} = - 1/{10^{ - 3}}$
$\therefore \;\frac{{ - 1}}{{{{10}^{ - 3}}}}( - L) = 4 \Rightarrow L = 4 \times {10^{ - 3}}henry$
$\therefore \;\frac{{ - 1}}{{{{10}^{ - 3}}}}( - L) = 4 \Rightarrow L = 4 \times {10^{ - 3}}henry$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
A student is performing the experiment of Resonance Column. The diameter of the column tube is $4$ $cm$. The frequency of the tuning fork is $512$ $Hz$. The air temperature is $38^o C$ in which the speed of sound is $336$ $m/s$. The zero of the meter scale coincides with the top end of the Resonance column tube. When the first resonance occurs, the reading of the water level in the column is ..... $cm$
→The parts of motor cars are polished by chromium because the angle of contact between water and chromium is
Find the velocity of image with respect to mirror.
In steady state graph between temp and distance from hot end is
The impact of an image on the retina remains for......$sec$
→There are two planets. The ratio of radius of the two planets is K but ratio of acceleration due to gravity of both planets is g. What will be the ratio of their escape velocity
If pressure of $C{O_2}$ (real gas) in a container is given by $P = \frac{{RT}}{{2V - b}} - \frac{a}{{4{b^2}}}$ then mass of the gas in container is ...... $gm$
→A straight wire carrying a current of $14\,A$ is bent into a semicircular are of radius $2.2\,cm$ as shown in the figure. The magnetic field produced by the current at the centre $(O)$ of the arc. is $.........\,\times 10^{-4}\, T$
→A current of $10\, amp$ is passing through a metallic wire of cross sectional area $4 \times 10^{-6}\, m ^{2}$. If the density of the aluminum conductor is $2.7\, gm / cc$ considering aluminum gives $1$ electrons per atom for conduction find the drift speed of the electrons is ......... $\times 10^{-4} \,m / s$ if molecular weight of aluminum is $27 \,gm$.
→The one division of main scale of vernier callipers reads $1\,mm$ and $10$ divisions of Vernier scale is equal to the $9$ divisions on main scale. When the two jaws of the instrument touch each other the $zero$ of the Vernier lies to the right of $zero$ of the main scale and its fourth division coincides with a main scale division. When a spherical bob is tightly placed between the two jaws, the $zero$ of the Vernier scale lies in between $4.1\,cm$ and $4.2\,cm$ and $6^{\text {th }}$ Vernier division coincides with a main scale division. The diameter of the bob will be $.............10^{-2}\,cm$
→