An electric dipole with dipole moment $\vec p = (3i + 4j) \times 10^{-30} C-m$ is placed in an electric field $\vec E = 4000 \hat i (N/C).$ An external agent turns the dipole slowly until its electric dipole moment becomes $(-4 \hat i + 3 \hat j) ×10^{-30}C-m.$ The work done by the external agent is equal to :-
Medium
Download our app for free and get started
Work done $ = {U_f} - {U_i} = {( - \overrightarrow p \cdot \overrightarrow E )_f} - {( - \overrightarrow p \cdot \overrightarrow E )_i}$
$=-\left(-16 \times 10^{-27}\right)-\left(-12 \times 10^{-27}\right)=2.8 \times 10^{-26} \mathrm{\,J}$
Download our appand get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Similar Questions
- 1The potential at a point $P$ due to an electric dipole is $1.8\times 10^5\,V$ . If $P$ is at a distance of $50\,cm$ apart from the centre $O$ of the dipole and if $CP$ makes an angle $60^o$ with the positive side of the axial line of the dipole, what is the moment of the dipole?View Solution
- 2A capacitor is charged with a battery and energy stored is $U$. After disconnecting battery another capacitor of same capacity is connected in parallel to the first capacitor. Then energy stored in each capacitor isView Solution
- 3A positively charged ring is in $y-z$ plane with its centre at origin. A positive test charge $q_0$, held at origin is released along $x$-axis, then its speedView Solution
- 4Two similar conducting balls having charges $+q$ and $-q$ are placed at a separation $d$ from each other in air. The radius of each ball is $r$ and the separation between their centres is $d(d > > r)$. Calculate the capacitance of the two ball systemView Solution
- 5In the connections shown in the adjoining figure, the equivalent capacity between $A$ and $B$ will be......$\mu F$View Solution
- 6A uniform electric field having a magnitude ${E_0}$ and direction along the positive $X - $ axis exists. If the potential $V$ is zero at $x = 0$, then its value at $X = + x$ will beView Solution
- 7A conducting sphere of radius $R$ is given a charge $Q.$ The electric potential and the electric field at the centre of the sphere respectively areView Solution
- 8Twenty seven drops of same size are charged at $220\, \mathrm{~V}$ each. They combine to form a bigger drop. Calculate the potential of the bigger drop. (In $\mathrm{~V}$)View Solution
- 9In one design of capacitor thin sheets ot metal of area $80\ mm \times 80\ mm$ sandwich between them a piece of paper whose thickness is $40\ μm$. The relative permittivity of the paper is $4.0$ and its dielectric strength is $20\ MVm^{-1}$. Calculate the maximum charge that can be put on the capacitorView Solution
[permittivity of free space $ = 9 \times 10^{-12}\ Fm^{-1}$]
- 10Two hollow conducting spheres of radii $R_{1}$ and $R_{2}$ $\left(R_{1}>>R_{2}\right)$ have equal charges. The potential would be:View Solution