Light of wavelength $$6000 \mathop A\limits^o$$ is incident on a thin glass plate of r.i. 1.5 such that the angle of refraction into the plate is $$60^{\circ}$$. Calculate the smallest thickness of the plate which will make dark fringe by reflected beam interference.
Consider a circuit where a cell of emf $$E_0$$ and internal resistance $$\mathrm{r}$$ is connected across the terminal $$\mathrm{A}$$ and $$\mathrm{B}$$ as shown in figure. The value of $$\mathrm{R}$$ for which the power generated in the circuit is maximum, is given by
The equivalent capacitance of a combination of connected capacitors shown in the figure between the points $$\mathrm{P}$$ and $$\mathrm{N}$$ is
In a single-slit diffraction experiment, the slit is illuminated by light of two wavelengths $$\lambda_1$$ and $$\lambda_2$$. It is observed that the $$2^{\text {nd }}$$ order diffraction minimum for $$\lambda_1$$ coincides with the $$3^{\text {rd }}$$ diffraction minimum for $$\lambda_2$$. Then