The velocity acquired by an electron at rest when subjected to a uniform electric field of potential difference 180 V is

(Mass of electron $=9 \times 10^{-31} \mathrm{~kg}$ and charge of electron $=1.6 \times 10^{-19} \mathrm{C}$ )

Charge ' $Q$ ' (in coulomb) flowing through a conductor in terms of time ' $t$ ' (in second) is given by the equation $Q=3 t^2+t$. The current in the conductor at time $t=3 \mathrm{~s}$ is

In a metal, the charge carrier density is $9.1 \times 10^{28} \mathrm{~m}^{-3}$ and its electrical conductivity is $6.4 \times 10^7 \mathrm{~S} \mathrm{~m}^{-1}$. When an electric field of $10 \mathrm{NC}^{-1}$ is applied to the metal, then the average time between two successive collisions of electrons in the metal is

(Mass of electron $=9.1 \times 10^{-31} \mathrm{~kg}$, charge of electron $=1.6 \times 10^{-19} \mathrm{C}$ )

The force per unit length on a straight wire carrying current of 8 A making an angle of $30^{\circ}$ with a uniform magnetic field of 0.15 T is