Q2.Electric potential energy of two point charges q and q0 is
Answer : Option BExplaination / Solution: Potential energy of a system of charges is the work done in assembling the charges. Force between two charges q and q0 placed at a distance r apart is F=q0q4πε0r2Potential energy of the charges is given by℧=∫∞r−F∙dr=∫∞r−q0q4πε0r2dr=qq04πε0r
Answer : Option CExplaination / Solution:
Ambiguous question. Energy may be gained or lost depending on the sign of the charge and the electric field. It can also remain unchanged if the charge moves perpendicular to the direction of the field.
Q4.Electric Potential V at a point in an electrical field is
Answer : Option DExplaination / Solution: Electric potential V is the work done in bringing unit positive charge from infinity to the point in an electric field, and the potential energy ℧is the work done in bringing any finite charge from infinity to the point in an electric field. They are related as, .If q =1C, ℧=V
Q6.If a positive charge moves in the direction of the electric field
Answer : Option BExplaination / Solution:
A positive charge experiences a force in the direction of the field. If it moves in the direction of the field, positive work is done by the electric field on the charge. Potential energy of the charge increases only when an external source does work on the charge against the direction of the field- eg: when the charge is moved against the direction of the field
Q7.If a positive charge moves opposite to the direction of the electric field
Answer : Option DExplaination / Solution:
A positive charge experiences a force in the direction of the field. If it moves opposite to the direction of the field, negative work is done by the electric field on the charge. Potential energy of the charge increases since an external source is required to do work on the charge against the direction of the field, and the work done is stored in the charge as its potential energy.
Answer : Option CExplaination / Solution: Electric potential V is the work done in bringing unit positive charge from infinity to the point in an electric field, and the potential energy ℧ is the work done in bringing any finite charge from infinity to the point in an electric field. They are related as,℧=qV V=℧q
Q10.Electric potential at a distance r from a point charges q is
Answer : Option DExplaination / Solution: Electric potential at a point V is the work done in bringing unit positive charge from infinity to the point in an electric field.V=∫∞r−E∙dr=∫∞r−q4πε0r2dr=q4πε0r
Total Question/Mark :
Scored Mark :
Mark for Correct Answer : 1
Mark for Wrong Answer : -0.5
Mark for Left Answer : 0