Electric charges and fields

 

Electric Charges and Fields

  
 Problems

 

Question1.  What is the value of charge on an electron? Is a charge less than this value possible?

Solution.  e = - 1.6 x 10-19 C.

                No, charge less than this value do not exist.

 Question2. Does the motion of a body affect its charge?

 Solution. No, charge on a body does not change with the motion of the body.

Question3. Give two points of distinction between charge and mass.

Solution. The charge can be positive, negative, or zero. But mass is a positive quantity. Further, the electric charge is always conserved. But mass is not conserved as it can be changed into energy and vice-versa.

Question4. What is the basic cause of the quantization of charge?

Solution. Only integral a number of electrons can be transferred from one body to the other.

Question5. Can ever photons have a charge? If not why?

Solution. No, photons can never have a charge. This is because charge cannot exist without rest mass.

Question6. Which of the following quantities depends on the state of rest or motion of a body?

 (a) Mass (b) length (c) time (d) charge (e) charge density and (I) phase?

Solution.  Mass, length, time, and charge density depend on the state of rest or motion of a body. However, charge and phase are invariant.

Question7. Does Coulomb's law of electric force obey Newton's third law of motion?

 Solution. Yes, it obeys. Forces exerted by two charges on each other are always equal and opposite.

Question8. Is the electric force between two electrons greater than the gravitational force between them? If so, by what factor?

Solution. Yes, the electric force between two electrons is greater than the gravitational force between them by a factor of 1042.

 Question9. Electrostatic forces are much stronger than gravitational forces. Give one example.

 Solution. A charged glass rod can lift a piece of paper against the gravitational pull of the earth on this piece.

Question10. What is the dimensional formula for ?

 Solution. [M-1 L-3 T4 A2 ].

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