- 1(current)
Q. No.| 1. | \(2~\text{mC}\) | 2. | \(8~\text{mC}\) |
| 3. | \(6~\text{mC}\) | 4. | \(4~\text{mC}\) |
The magnitude of electric field intensity at a distance \({R}~(R \gg L )\) varies as:
| 1. | \(\dfrac{1}{{R}^{6}}\) | 2. | \(\dfrac{1}{{R}^{2}}\) |
| 3. | \(\dfrac{1}{{R}^{3}}\) | 4. | \(\dfrac{1}{{R}^{4}}\) |
Polar molecules are the molecules:
| 1. | that acquires a dipole moment only when the magnetic field is absent. |
| 2. | has a permanent electric dipole moment. |
| 3. | has zero dipole moment. |
| 4. | that acquire a dipole moment only in the presence of an electric field due to displacement of charges. |
A dipole is placed in an electric field as shown. In which direction will it move?
| 1. | towards the left as its potential energy will decrease. |
| 2. | towards the right as its potential energy will increase. |
| 3. | towards the left as its potential energy will increase. |
| 4. | towards the right as its potential energy will decrease. |
(\(r\gg\) separation of two charges forming the dipole, \(\varepsilon_{0} =\) permittivity of free space)
| 1. | \(\overrightarrow{E}=\dfrac{\overrightarrow{P}}{4\pi \varepsilon _{0}r^{3}}\) | 2. | \(\overrightarrow{E}=\dfrac{2\overrightarrow{P}}{\pi \varepsilon _{0}r^{3}}\) |
| 3. | \(\overrightarrow{E}=-\dfrac{\overrightarrow{P}}{4\pi \varepsilon _{0}r^{2}}\) | 4. | \(\overrightarrow{E}=-\dfrac{\overrightarrow{P}}{4\pi \varepsilon _{0}r^{3}}\) |
| 1. | \(8~\text{mC}\) | 2. | \(2~\text{mC}\) |
| 3. | \(5~\text{mC}\) | 4. | \(7~\mu \text{C}\) |
Three-point charges \(+q\), \(-2q\) and \(+q\) are placed at points \((x=0,y=a,z=0)\), \((x=0, y=0,z=0)\) and \((x=a, y=0, z=0)\), respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are:
| 1. | \(\sqrt{2}qa\) along \(+y\) direction |
| 2. | \(\sqrt{2}qa\) along the line joining points \((x=0,y=0,z=0)\) and \((x=a,y=a,z=0)\) |
| 3. | \(qa\) along the line joining points \((x=0,y=0,z=0)\) and \((x=a,y=a,z=0)\) |
| 4. | \(\sqrt{2}qa\) along \(+x\) direction |
A dipole with moment \(\vec p\) is placed in a uniform electric field \(\vec E\). The torque acting on the dipole is given by:
1. \(\vec{\tau }=\vec{p}\cdot \vec{E}\)
2. \(\vec{\tau }=\vec{p} \times \vec{E}\)
3. \(\vec{\tau }=\vec{p}+ \vec{E}\)
4. \(\vec{\tau }=\vec{p}- \vec{E} \)
The electric field at the equator of a dipole is \(E.\) If the strength of the dipole and distance are now doubled, then the electric field will be:
| 1. | \(E/2\) | 2. | \(E/8\) |
| 3. | \(E/4\) | 4. | \(E\) |
A point \(Q\) lies on the perpendicular bisector of an electric dipole of dipole moment \(p.\) If the distance of \(Q\) from the dipole is \(r\) (much larger than the size of the dipole), then the electric field at \(Q\) is proportional to:
1. \(p^{2}\) and \(r^{-3}\)
2. \(p\) and \(r^{-2}\)
3. \(p^{-1}\) and \(r^{-2}\)
4. \(p\) and \(r^{-3}\)
- 1(current)
Q. No.
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