Question
A long, straight wire carries a current. Is Ampere's law valid for a loop that does not enclose the wire? That encloses the wire but is not circular?
✓
Answer
Ampere's law is valid for a loop that is not circular. However, it should have some charge distribution in the area enclosed so as to have a constant electric field in the region and a non-zero magnetic field. Even if the loop defined does not have its own charge distribution but has electric influence of some other charge distribution, it can have some constant magnetic field $\big(\oint\overrightarrow{\text{B}}.\text{d}\overrightarrow{\text{l}}=\mu_0\text{i}\ \text{enclosed}\big).$
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
An inductor-coil, a capacitor and an AC source of rms voltage 24V are connected in series. When the frequency of the source is varied, a maximum rms current of 6.0A is observed. If this inductor coil is connected to a battery of emf 12V and internal resistance $4.0\Omega,$ what will be the current?
→The average translational kinetic energy of air molecules is $0.040\ eV (1\ eV = 1.6 \times 10^{-19}J)$. Calculate the temperature of the air. Boltzmann constant $k = 1.38 \times 10^{-23}JK^{-1}$.
→- Define self $-$ inductance. Write its $SI$ units.
- A long solenoid with $15$ turns per $\ cm$ has a small loop of area $2.0 \ cm^2$ placed inside the solenoid normal to its axis. If the current carried by the solenoid changes steadily from $ 2.0 A$ to $4.0 A$ in $0.1 s,$ what is the induced emf in the loop while the current is changing?
A square coil of edge l and with n turns carries a current i. It is kept on a smooth horizontal plate. A uniform magnetic field B exists parallel to an edge. The total mass of the coil is M. What should be the minimum value of B for which the coil will start tipping over?
The band gap between the valence and the conduction bands in zinc oxide (ZnO) is 3.2eV. Suppose an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation. Find the maximum wavelength that can be emitted in this process.
Explain how the scattering experiment can be analyzed in detail from Rutherford's nuclear model.
Calculate the maximum kinetic energy of the beta particle emitted in the following decay scheme :
$\text{ }^{12}\text{N}\rightarrow{ }^{12}\text{C}^*+\text{e}^++\text{v}$
$\text{ }^{12}\text{C}^*\rightarrow\text{ }^{12}\text{C}+\gamma(4.43\ \text{MeV}).$
The atomic mass of $^{12}N$ is $12.018613u$.
→$\text{ }^{12}\text{N}\rightarrow{ }^{12}\text{C}^*+\text{e}^++\text{v}$
$\text{ }^{12}\text{C}^*\rightarrow\text{ }^{12}\text{C}+\gamma(4.43\ \text{MeV}).$
The atomic mass of $^{12}N$ is $12.018613u$.
Figure, shows an aluminium wire of length $60\ cm$ joined to a steel wire of length $80\ cm$ and stretched between two fixed supports. The tension produced is $40N$. The cross$-$sectional area of the steel wire is $1.0\ mm^2$ and that of the aluminium wire is $3.0\ mm^2.$ What could be the minimum frequency of a tuning fork which can produce standing waves in the system with the joint as a node? The density of aluminium is $2.6\ g/cm^3$ and that of steel is $7.8\ g/cm^3.$
→The magnetic field due to a long straight wire has been derived in terms of $\mu_0,$ i and d. Express this in terms of $\epsilon_0,$ C, i and d.
→- Explain with the help of a diagram formation of depletion region and barrier potential in a $pn$ junction.
- Draw the circuit diagram of a half wave rectifier and explain its working.