A polythene piece rubbed with wool is found to have a negative charge of . Transfer of mass from wool to polythene is:
1. 0.7 × 10 - 18 kg
2. 1.7 × 10 - 17 kg
3. 0.7 × 10 - 17 kg
4. 1.7 × 10 - 18 kg
In a certain region of space, the electric field is along the z-direction throughout. The magnitude of the electric field is, however, not constant but increases uniformly along the positive z-direction, at the rate of 105 NC-1 per meter. What is the torque experienced by a system having a total dipole moment equal to in the negative z-direction?
1. | 2. | ||
3. | 4. |
A hollow metal sphere of radius \(R\) is uniformly charged. The electric field due to the sphere at a distance \(r\) from the centre:
1. | decreases as \(r\) increases for \(r<R\) and for \(r>R\). |
2. | increases as \(r\) increases for \(r<R\) and for \(r>R\). |
3. | is zero as \(r\) increases for \(r<R\), decreases as \(r\) increases for \(r>R\). |
4. | is zero as \(r\) increases for \(r<R\), increases as \(r\) increases for \(r>R\). |
Two point dipoles of dipole moment and are at a distance x from each other and . The force between the dipole is:
1.
2.
3.
4.
A spherical conductor of radius \(10~\text{cm}\) has a charge of \(3.2 \times 10^{-7}~\text{C}\) distributed uniformly. What is the magnitude of the electric field at a point \(15~\text{cm}\) from the center of the sphere? \(\frac{1}{4\pi \varepsilon _0} = 9\times 10^9~\text{N-m}^2/\text{C}^2\)
1. \(1.28\times 10^{5}~\text{N/C}\)
2. \(1.28\times 10^{6}~\text{N/C}\)
3. \(1.28\times 10^{7}~\text{N/C}\)
4. \(1.28\times 10^{4}~\text{N/C}\)
If there were only one type of charge in the universe, then,
1. | on any surface. |
2. | if the charge is outside the surface. |
3. | could not be defined. |
4. | if charges of magnitude q were inside the surface. |
Refer to the arrangement of charges in the figure and a Gaussian surface of radius R with Q at the centre. Then:
a. | total flux through the surface of the sphere is . |
b. | field on the surface of the sphere is . |
c. | flux through the surface of the sphere due to 5Q is zero. |
d. | field on the surface of the sphere due to -2Q is the same everywhere. |
Choose the correct statement(s):
1. a and d
2. a and c
3. b and d
4. c and d
The electric field at a point on the equatorial plane at a distance \(r\) from the centre of a dipole having dipole moment \(\overrightarrow{P}\) is given by:
(\(r\gg\) separation of two charges forming the dipole, \(\epsilon_{0} =\) permittivity of free space)
1. \(\overrightarrow{E}=\frac{\overrightarrow{P}}{4\pi \epsilon _{0}r^{3}}\)
2. \(\overrightarrow{E}=\frac{2\overrightarrow{P}}{\pi \epsilon _{0}r^{3}}\)
3. \(\overrightarrow{E}=-\frac{\overrightarrow{P}}{4\pi \epsilon _{0}r^{2}}\)
4. \(\overrightarrow{E}=-\frac{\overrightarrow{P}}{4\pi \epsilon _{0}r^{3}}\)
The acceleration of an electron due to the mutual attraction between the electron and a proton when they are \(1.6~\mathring{A}\) apart is:
( \(\frac{1}{4 \pi \varepsilon_0}=9 \times 10^9~ \text{Nm}^2 \text{C}^{-2}\) )
1. | \( 10^{24} ~\text{m/s}^2\) | 2 | \( 10^{23} ~\text{m/s}^2\) |
3. | \( 10^{22}~\text{m/s}^2\) | 4. | \( 10^{25} ~\text{m/s}^2\) |
Four charges are arranged at the corners of a square ABCD as shown in the figure. The force on a positive charge kept at the center of the square is:
1. | Zero |
2. | Along diagonal AC |
3. | Along diagonal BD |
4. | Perpendicular to the side AB |