If an alternating voltage is applied across a p-n junction diode in series with a load then

Two waves of same frequency ( n ) are approaching each other with same velocity $12 \mathrm{~m} / \mathrm{s}$ along the same linear path and interfere. The distance between two consecutive nodes is

A coil of resistance $400 \Omega$ is placed in ${ }^3$ magnetic field. If the magnetic flux ' $\phi$, ( Wb ) linked with the coil varies with time ' $t$ ' ( $s$ ) ${ }^{\text {is }} \phi=50 \mathrm{t}^2+4$, the current in the coil at $\mathrm{t}=2 \mathrm{~s}$ will be