Five capacitors, each of capacitance ' $C$ ' are connected as shown in the figure. The ratio of equivalent capacitance between P and R and the equivalent capacitance between P and Q is

Let $E_c$ and $E_p$ represents kinetic energy of electron and photon respectively. If de-Broglie wavelength of a photon is twice the de-Broglie wavelength of an electron then $E_p / E_c$ is (speed of electron $=\mathrm{C} / 100$ where C is the velocity of light)

The fundamental frequency of an air column in a pipe closed at one end is 150 Hz . If the same pipe is open at both the end, the frequencies produced in Hz are

When the observer moves towards a stationary source with velocity $\mathrm{V}_1$, the apparent frequency of emitted note is $F_1$. When observer moves away from the source with velocity $\mathrm{V}_1$, the apparent frequency is $\mathrm{F}_2$. If V is the velocity of sound in air and $F_1 / F_2=2$ then $V / V_1$ is equal to