We can charge a metal sphere positively without touching it by:
1. Conduction
2. Induction
3. Friction
4. Both (1) and (2)
If electrons move out of a body to another body every second, how much time approximately is required to get a total charge of C on the other body?
1. years
2. years
3. years
4. years
The amount of positive and negative charges in a cup of water ( g) are respectively:
1. | C, C |
2. | C, C |
3. | C, C |
4. | C, C |
The ratio of the magnitude of electric force to the magnitude of gravitational force for an electron and a proton will be:
(, )
1.
2.
3.
4.
A charged metallic sphere is suspended by a nylon thread. Another identical charged metallic sphere held by an insulating handle is brought close to such that the distance between their centres is cm, as shown in Fig.(a). The resulting repulsion of is noted. Then spheres and are touched by identical uncharged spheres and respectively, as shown in Fig.(b). and are then removed and is brought closer to to a distance of cm between their centres, as shown in Fig. (c). What is the expected repulsion on on the basis of Coulomb’s law?
1. | Electrostatic force on due to remains unaltered. |
2. | Electrostatic force on due to becomes double. |
3. | Electrostatic force on due to becomes half. |
4. | Can't say. |
Consider three charges each equal to at the vertices of an equilateral triangle of side What is the force on a charge (with the same sign as ) placed at the centroid of the triangle, as shown in the figure?
1.
2.
3. zero
4.
Consider the charges and placed at the vertices of an equilateral triangle, as shown in the figure. Then the sum of the forces on the three charges is:
1.
2. zero
3.
4.
An electron falls through a distance of in a uniform electric field of magnitude [figure (a)]. The direction of the field is reversed keeping its magnitude unchanged and a proton falls through the same distance [figure (b)]. If and are the time of fall for electron and proton respectively, then:
1.
2.
3.
4. none of these
Two-point charges and , of magnitude and , respectively, are placed 0.1 m apart. The electric field at point A (as shown in the figure) is:
Two charges are placed mm apart. The electric field at a point on the axis of the dipole cm away from its centre on the side of the positive charge, as shown in the figure is:
1. | 2. | ||
3. | 4. |