Physics M.C.Q (1 Marks)

Though gold is a costly metal it is used in electroscope because of the property malleability. This means very thin and light sheets can be formed from gold simply by hammering or rolling and hence the deflection of the light gold plates increases.

Needle end can arrest the lightning easily. Besides, the device must provide a continuous path to electricity so that current passes to ground. It must have a high melting point else it will meltdown due to the heat generated during carrying lightning current.

Depending on the nature and quantity of charges, the net force on the central charge may vary its magnitude and direction. If all the charges are the same the net force will be zero.

A target is present at any point of field line.
The target at any point of the field lines generaly gives the elective field at that point.

Dipole is defined as two equal but opposite charges, kept at a small distance and having a dipole moment. The dipole moment is simply the product of the electric charge and length of the dipole. The dielectric constant of the medium doesn’t affect the dipole moment i.e. dipole moment of an electric dipole will be the same in water as well as in the air.

Electric lines of force are imaginary.

We have to find the nature of charges on upper edges of clouds in a thunderstorm, the air currents move upwards while the water droplets move downward. This vigorous movement causes separation of charges. This leads to the positive charges collected near the upper edges of clouds and the negative charges to accumulate near the lower edges of the clouds.

We should not touch the electric appliance with bare hands. To check the supply in the circuit, the electric tester should be used.

Coulomb's law: The force exerted by one point charge is proportional to the product of the charge and varies inversely as the sure of the distance separating the charges.

Coulomb’s Law explains the force between two point charges only. A distributed charge can be considered as the sum of infinite point charges and thus the force between two distributed charge systems can be explained.

Force between two charges is inversely proportional to the relative permittivity of the medium between them. A dielectric slab has relative permittivity more than that of air. So the force between the charges decreases. No current or heating will be noticed.

Charge remains on the outer surface of a conductor, irrespective of the shape and size of the conductor and also for hollow and solid conductors both. But if there is a sharp edge in the conductor, surface charge density will be more at that point. The surface charge density is uniform in the case of a sphere.

If a ordinary glass rod is rubbed on the silk cloth is brought near bits of paper, it is found that they have acquired the attractive property. The glass rod get charged on rubbing.

When an electron enters an electric field with its velocity in the direction of the electric lines of field, then the velocity of the electron will decrease just after entry due to the lines of force of the electric field.