# Dipole Moment

## Trending Questions

**Q.**

A system has two charges qA=2.5×10−7C and qB=−2.5×10−7C located at points A(0, 0, -15cm) and B(0, 0, +15cm), respectively. What are the total charge and electric dipole moment of the system?

**Q.**Three charges Q, +q and +q are placed at the vertices of a right angled isosceles triangle as shown in figure. The net electrostatic energy of the configuration is zero, if Q is equal to

- −q1+√2
- −2q
- −√2q1+√2
- +q

**Q.**

Consider the force $F$ on a charge $q$ due to a uniformly charged spherical shell of radius $R$ carrying charge $Q$ distributed uniformly over it. Which one of the following statements is true for $F$, if $q$ is placed at distance $r$ from the center of the shell?

$F=\frac{1}{4{\mathrm{\pi \epsilon}}_{0}}\frac{qQ}{{R}^{2}}>F>0forr<R$

$F=\frac{1}{4{\mathrm{\pi \epsilon}}_{0}}\frac{qQ}{{r}^{2}}forr>R$

$F=\frac{1}{4{\mathrm{\pi \epsilon}}_{0}}\frac{qQ}{{r}^{2}}forallr$

$F=\frac{1}{4{\mathrm{\pi \epsilon}}_{0}}\frac{qQ}{{R}^{2}}forr<R$

**Q.**An electric dipole is placed in an electric field generated by a point charge. Then

- net electric force on the dipole must be zero
- net electric force on the dipole may be zero
- torque on the dipole due to the field must be zero
- torque on the dipole due to the field may be zero

**Q.**An electric dipole is placed in a uniform electric field. The net electric force on the dipole

- is always zero
- depends on the orientation of the dipole
- can never be zero
- depends on the strength of the electric field

**Q.**A neutral water molecule (H2O) in its vapor state has an electric dipole moment of magnitude 6.4×10–30 C-m. How far apart are the centres of positive and negative charge?

- 4mm

- 4pm
- 4m

- 4μm

**Q.**(a) Use Gauss' law to derive the expression for the electric field (E) due to a straight uniformly charged infinite line of charge density λ C/m.

(b) Draw a graph to show the variation of E with perpendicular distance r from the line of charge.

(c) Find the work done in bringing a charge q from perpendicular distance r1 to r2(r2>r1).

**Q.**The electric field due to an electric dipole at a distance r from its center on the axial line is E. If the dipole is rotated through an angle of 90∘ about its perpendicular axis, electric field at the same point will be

- E2
- E
- 2E
- E4

**Q.**

Three charges are arranged on the vertices of an equilateral triangle as shown in figurre (29-E6). Find the eipole moment of the combination.

**Q.**A short dipole is placed at origin of coordinate system in x-y plane as shown in figure. Find the electric field at point P(0, y). (y>> length of dipole)

- Kp2y3[−2ˆi−ˆj]
- 2Kpy3[−2ˆi−ˆj]
- √2Kpy3[−ˆi−2ˆj]
- Kp√2y3[−ˆi−2ˆj]

**Q.**A ball of mass 1g and charge 10^{-8} C moves from point A, where potential is 600V to the point where potential is zero.Velocity of the ball at point B is 20cm/s.The velocity of the ball at point A will be a)22.8 cm/s b)228 cm/s c)16.8 cm/s d)168 cm/

**Q.**

Two charges +3.2×10−19Cand−3.2×10−19C placed 2.4Ao apart form an electric dipole. It is placed in a uniform electric field of intensity 4×105Vm−1 , the workdone to rotate the electric dipole from the equilibrium position by 180o is ......×10−23J

**Q.**At a far away distance r along the axis from an electric dipole, the electric field is E. Find the electric field at distance 2r along the perpendicular bisector.

- -E4
- -E16
- E2
- E

**Q.**What is the angle between the electric dipole moment and the electric field strength due to it on the equatorial line

- 0∘
- 45∘
- 90∘
- 180∘

**Q.**A positive point charge q is fixed at origin. A short dipole with a dipole moment p is placed along the x−axis far away from the origin with p pointing along the +x−axis. The kinetic energy of the dipole when it reaches distance d from origin is

- 3qp8πϵ0d2
- qp4πϵ0d2
- 2qp4πϵ0d2
- qp16πϵ0d2

**Q.**Two short electric dipoles of moment P and 27P are placed as shown below. If at the point O the electric field is zero between the dipoles, then the distance of the point O from the centre of first dipole is

- 2 cm
- 4 cm
- 6 cm
- 8 cm

**Q.**The magnitude of force due to an electric dipole of dipole moment 3.6×10−29 C-m on an electron 25 nm from the centre of the dipole along the dipole axis is

- 6.6×10−15 N
- 7.8×10−15 N
- 9.4×10−15 N
- 12×10−15 N

**Q.**Two identical electric dipoles are arranged on x-axis as shown in figure. Electric field at the origin will be ( Assume 14πϵ0=K )

- zero
- Kp√2r3^j
- −Kp√2r3^j
- 2Kpr3^i−kpr3^j

**Q.**

Two particles, carrying charges - q and +q and having equal masses m each are fixed at the ends of a light rod of length a to form a dipole. The rod is clamped at an end and is placed in a uniform electric field E with slightly tilted and then released. Neglecting gravity find the time period of small oscillations.

**Q.**Point charges q, q, -2q are placed at the corners of an equilateral triangle ABC of side l. The magnitude of net electric dipole moment of the system is

- 4ql
- ql
- 2ql
- √3ql

**Q.**A short dipole is placed along x− axis with centre at origin (O). The electric field at a point P due to dipole such that −−→OP makes an angle of 45∘ with the x− axis, is directed along a direction making

- tan−1(0.5) with x− axis
- π4+tan−1(0.5) with x− axis
- π4+tan−1(0.5) with y− axis
- tan−1(0.5) with y− axis

**Q.**Find the maximum value of torque acting on the dipole placed in a uniform electric field as shown in figure.

- 10−6 N-m
- 2×10−6 N-m
- 3×10−6 N-m
- Data insufficient

**Q.**An electron and a proton are at a distance of 1˙A. The dipole moment will be (C×m)

- 1.6×1019
- 1.6×10−29
- 3.2×1019
- 3.2×1029

**Q.**

Two particles A and B having oposite charges 2.0×10−6C and −2.0×10−6C, are placed at a separation of 1.0 cm. (a) Write down te electric diple moment of this pair. (b) calculate the electric field at a Point on the axis of the dipole 1.0 m away from the centre. (c) Calculat the electric field at a point on the perpendicular bisector of the dipole and 1.0 m away from the centre.

**Q.**What is an electric dipole? Define electric dipole moment?

**Q.**The linear charge density upon the semicircular ring, on both side is same in magnitude i.e. µ but different in nature, what is the magnitude of electric field intensity at center?

**Q.**

For uniform electric field, field lines are _______

**Q.**Initially the capacitor is uncharged , find the charge on capacitor as a function of time, if switch is closed at t=0.

- q=εC2(1−e−2t3RC)
- q=εC2(1−e−tRC)
- q=εC2(1−e−t2RC)
- q=3εC2⎡⎢ ⎢⎣1−e⎡⎣−2tRC⎤⎦⎤⎥ ⎥⎦

**Q.**A positive point charge q is fixed at origin. a small dipole with a dipole moment →p is placed along the x-axis far away from the origin with →p pointing along positive x-axis. Find the kinetic energy of the dipole when it reaches a distance d from the origin.

- qp4πϵ0d2
- 2 qpπϵ0d2
- qp2πϵ0d2
- 4 qpπϵ0d2

**Q.**in a spherical capacitor with plate radii a and b, the potential difference between the plates is V . the electric field between the plates at a radial dis†an ce r from the centre is