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 $=1.6 \times 10^{-19} \mathrm{C}$ )

A straight wire of resistance $18 \Omega$ is bent in the form of an equilateral triangular loop. The effective resistance between any two vertices of the triangle is

The power dissipated by a uniform wire of resistance $100 \Omega$ when a potential difference of 120 V is applied across its ends is