A proton is kept at rest. A positively charged particle is released from rest at a distance S in its field. Consider two experiments; one in which the charged particle is also a proton and in another, a positron. In the same time t, the work done on the two moving charged particles is
1. same as the same force law is involved in the two experiments.
2. less for the case of a positron, as the positron moves away more rapidly and the force on it weakens.
3. more for the case of a positron, as the positron moves a larger distance away.
4. same as the work is done by a charged particle on the stationary proton.
A positively charged insulator is brougnt near(but does not touch) two metallic spheres that are in contact. The metallic spheres are then separated. The sphere which was initially farthest from the insulator will have:
1. no net charge
2. a negative charge
3. a positive charge
4. either a negative or a positive charge.
In the electric field of a point charge q, a certain charge is carried from point A to B, C, D, and E, the work done:
1. is least along the path AB
2. is least along the path AD
3. is zero along any one of the paths AB, AC and AE
4. is least along AE.
In a Millikan-type experiment, there are two oil droplets P and Q between the charged horizontal plates, as shown in the diagram. Droplet P is in rest while droplet Q is moving upwards. The polarity of the charges on P and Q is
P Q
1. + +
2. Neutral -
3. - -
4. + -
In the figure below, a point charge +Q1 is at the centre of an imaginary spherical Gaussian surface and another point charge +Q2 is outside of the Gaussian surface. Point P is on the surface of the sphere. Which one of the following statements is true ?
1. Both charges +Q1 and +Q2 contribute to the net electric flux through the sphere but only charge +Q1 contributes to the electric field at point P on the sphere.
2. Both charges +Q1 and +Q2 contribute to the net electric flux through the sphere but +Q2 contributes to the electric field at point P on the sphere.
3. Only the charge +Q1 contributes to the net electric flux through the sphere but both charges +Q1 and +Q2 contribute to the electric field at point P.
4. Only the charge +Q2 contributes to the net electric flux through the sphere but both charges +Q1 and +Q2 contribute to the electric field at point P.
Two identical infinite positive line charges are placed along the lines , in the x-y plane. A positive point charge placed at origin is restricted to move along y-axis. Its equilibrium is:
1. Stable
2. Neutral
3. Unstable
4. None of these
The variation of electric field between the two charges q1 and q2 along the line joining the charges is plotted against distance from q1 (taking rightwards direction of field as positive) as shown, then the correct statement is:
1. q1 and q2 are positive and q1 < q2
2. q1 and q2 are positive and q1 > q2
3. q1 is positive and q2 is negative
4. q1 is positive and q2 is negative and q1 < |q2|
| (a) | \(\oint_s {E} . {dS} \neq 0\) on any surface |
| (b) | \(\oint_s {E} . {dS} = 0\) if the charge is outside the surface. |
| (c) | \(\oint_s {E} . {dS}\) could not be defined. |
| (d) | \(\oint_s {E} . {dS}=\frac{q}{\epsilon_0}\) if charges of magnitude \(q\) were inside the surface. |
| 1. | (a) and (d) | 2. | (a) and (c) |
| 3. | (b) and (d) | 4. | (c) and (d) |
| (a) | the electric field is necessarily zero. |
| (b) | the electric field is due to the dipole moment of the charge distribution only. |
| (c) | the dominant electric field is \(\propto \dfrac 1 {r^3}\), for large \(r\), where \(r\) is the distance from the origin in this region. |
| (d) | the work done to move a charged particle along a closed path, away from the region, will be zero. |
Which of the above statements are true?
1. (b) and (d)
2. (a) and (c)
3. (b) and (c)
4. (c) and (d)
Refer to the arrangement of charges in the figure and a Gaussian surface of a radius \(R\) with \(Q\) at the centre. Then:
| (a) | total flux through the surface of the sphere is \(\frac{-Q}{\varepsilon_0}.\) |
| (b) | field on the surface of the sphere is \(\frac{-Q}{4\pi \varepsilon_0 R^2}.\) |
| (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) |
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