When two light waves each of amplitude '$$A$$' and having a phase difference of $$\frac{\pi}{2}$$ superimposed then the amplitude of resultant wave is
In an n-p-n transistor, the collector current is $$28 \mathrm{~mA}$$. If $$80 \%$$ of electrons reach the collector, its base current in $$\mathrm{mA}$$ is
A light spring is suspended with mass $$m_1$$ at its lower end and its upper end fixed to a rigid support. The mass is pulled down a short distance and then released. The period of oscillation is $$T$$ second. When a mass $$m_2$$ is added to $$m_1$$ and the system is made to oscillate, the period is found to be $$\frac{3}{2} T$$. The ratio $$m_1: m_2$$ is
The molecular mass of a gas having r.m.s. speed four times as that of another gas having molecular mass 32 is