Question

Figure shows a siphon. The liquid shown is water. The pressure difference P_B − P_A between the points A and B is
(a) 400 Nm⁻²
(b) 3000 Nm⁻²
(c) 1000 Nm⁻²
(d) zero

Answer 1

(d) zero

At both points A and B, pressure is equal to atmospheric pressure.

$$\begin{gathered} \mathrm{Thus},\mathrm{we}\mathrm{have}: \\ {P}_{\mathrm{A}}=P_{\mathrm{B}}=P_{\mathrm{atm}} \\ \Rightarrow P_{\mathrm{B}}-P_{\mathrm{A}}=0 \end{gathered}$$