Q .) It is found that 1020 electrons, each having a charge of
1.6 × 10-19 C, pass from a point X towards another point Y
in 0.1s. What is the current and its direction ?
q = ne = 10 20 × 1.6 × 10 -19 = 16C; t = 0.1s
∴ I = q/t = 16/0.1 = 160A
The direction of convectional current is from the point Y to X.
Q. ) What is conventional current ?
Ans. The Current that flows from poitive pole to negative pole of a cell in the
external circuit is called convectional current.
Q. ) What is the direction of conventional current ?
Ans. In an electric circuit, the direction of convectional electric current is
form positive to negative terminal of the battery.
Q. ) What is the Significance of direction of electric current ?
Ans. The direction of conventional electric current is opposite to the direction
of flow of electrons and the direction of electronic current is same as that
of the flow of electrons.
Q. ) Define SI unit of Current? ?
Ans. The current through a conductor is called one ampere, if one coulomb of charge
flows through the conductor in one second.
Q. ) Write down the relation between a coulomb and an ampere.
Ans. 1 ampere = 1 coloumb/1 Second
Q .) Define drift velocity of an electron ?
Ans. The drift velocity is defined as the average velocity with which free electrons
in a conductor get drifted under the influence of an external electric field
applied across the conductor.
Q .) How does the drift velocity of electrons in a metallic conductor vary with increase in
Ans. The drift velocity of electrons in a metallic conductor decrease with increase in
temperature of the conductor.
Q .) A steady current flows in a metallic conductor of non-uniform cross-section. Explain
which of these quantities is constant along the conductor: Current, Current density,
electric field and drift speed ?
Ans. Except current, the value of all the quantities depends upon the area of
cross-section of the conductor. Hence, only current remains constant, when it flows
through a conductor of non-uniform area of the cross-section.
Does the value of resistance of a conductor depend upon the potential difference
applied across it or the current passed through it ?
Ans. No, the resistance of a conductor does not depend upon the potential difference
applied across it or the current passed through it.