MCQ
Find force per unit length at $P$.
- A$10^{-4}\, m$
- ✓$10^{-4} \,N / m$
- C$3 \times 10^{-4}\, N / m$
- D$0.3\, N / m$
✓
Answer
Correct option: B.
$10^{-4} \,N / m$
b
The magnetic field at $B$,
The magnetic field at $B$,
$B=\frac{\mu_{0} i}{4 \pi r}+0+\frac{\mu_{0} i}{4 \pi r}$
$=\frac{\mu_{0} \times 5}{4 \pi \times 5 \times 10^{-2}} \times 2$
$=\frac{\mu_{0}}{4 \pi} \times 200$
$=2 \times 10^{-5} T$
Consider the length of wire element at $P$ is $dl$.
The force per unit length at $P$ is,
$F=i B d l$
$\frac{F}{d l}=i B$
$=5 \times 2 \times 10^{-5}$
$=10^{-4} N / m$
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 non-conducting solid sphere of radius $R$ is uniformly charged. The magnitude of the electric field due to the sphere at a distance $r$ from its centre
→An infinitely long solid cylinder of radius $R$ has a uniform volume charge density $\rho$. It has a spherical cavity of radius $R / 2$ with its centre on the axis of the cylinder, as shown in the figure. The magnitude of the electric field at the point $P$, which is at a distance $2 \ R$ from the axis of the cylinder, is given by the expression $\frac{23 \rho R }{16 k \varepsilon_0}$. The value of $k$ is
→Two spheres $A$ and $B$ of radius $a$ and $b$ respectively are at same electric potential. The ratio of the surface charge densities of $A$ and $B$ is
→Consider the two idealised systems: (i) a parallel plate capacitor with large plates and small separation and (ii) a long solenoid of length L > > R, radius of cross-section. In (i), E is ideally treated as a constant between plates and zero outside. In (ii), magnetic field is constant inside the solenoid and zero outside. These idealised assumptions, however, contradict fundamental laws as below:
An arc of a circle of radius R subtends an angle $\frac{\pi}{2}$ at the centre. It carries a current i. The magnetic field at the centre will be
→A single slit of width $a$ is illuminated by a monochromatic light of wavelength $600\,nm$. The value of $a$ for which first minimum appears at $\theta=30^{\circ}$ on the screen will be ........... $\mu m$
→Two electric lamps of 40 watt each are connected in parallel. The power consumed by the combination will be
A hydrogen atom, initially in the ground state is excited by absorbing a photon of wavelength $980\,\mathop A\limits^o $. The radius of the atom in the excited state, in terms of Bohr radius $a_0,$ will be $(hc\,=\,12500\,eV-\mathop A\limits^o)$
→The frequency of oscillation of current in the inductor is.
In Rutherford's experiment, number of particles scattered at $90^{\circ}$ angle are $x$ per second. Number particles scattered per second at angle $60^{\circ}$ is
→