NEET Physics Current Electricity MCQs

A conductor of cross-sectional area $1 imes 10^{-6} m^2$ carries a current of 4A. If the number density of free electrons is $10^{28} m^{-3}$, and the charge on an electron is $1.6 imes 10^{-19} C$, what is the magnitude of the drift velocity of the electrons, assuming they all contribute to the current?

Two copper wires of equal length but different cross-sectional areas carry the same current. Which of the following statements is true regarding the drift velocities of electrons in the two wires?

A metallic conductor has a current of 5A flowing through it. The free electron density is $8.5 imes 10^{28} m^{-3}$. The cross-sectional area of the conductor is $2 imes 10^{-6} m^2$. If the average relaxation time is $2 imes 10^{-14} s$ and the electric field strength inside the conductor is 2 V/m, what is the mass of an electron (approximately)? (Assume the charge of an electron is $1.6 imes 10^{-19} C$).

Consider a conductor with a non-uniform cross-sectional area. If a steady current flows through it, which of the following quantities remains constant along the length of the conductor?

A cylindrical copper conductor with radius $r_1$ carries a current $I$. If the radius is doubled to $2r_1$ while keeping the current the same, and assuming the electric field within the conductor remains uniform, how does the drift velocity of electrons change?

A copper wire of cross-sectional area $1 imes 10^{-6} m^2$ carries a current of 1 A. Assuming that each copper atom contributes one free electron, calculate the drift velocity of the electrons. Given: density of copper = $9 imes 10^3 kg/m^3$, atomic weight of copper = 63.5 g/mol, Avogadro's number = $6.02 imes 10^{23} mol^{-1}$.

If the current in a conductor is doubled, keeping the area of cross-section and the number density of charge carriers constant, the drift velocity:

Two wires, A and B, made of the same material and having the same length, carry the same current. If the cross-sectional area of A is twice that of B, the ratio of their drift velocities ($v_{dA} : v_{dB}$) is:

A conductor has a cross-sectional area of $10^{-6} m^2$. If $10^{19}$ electrons pass through this area per second, what is the current flowing through the conductor? (Charge of an electron = $1.6 imes 10^{-19} C$)

If the current flowing through a conductor is doubled, keeping the cross-sectional area and electron density constant, the drift velocity will: