TG EAMCET 3 May 2025 Shift 2 Paper

When you pull the wires apart, the water film stretches, making its area bigger.
A thin film has two surfaces (top and bottom), so the increase in area is:
∆A=2×L×∆d
Let's define what we have:
Length of each wire, L=8cm=0.08m
Starting distance, d1=0.6cm=0.006m
Final distance, d2=0.8cm=0.008m
Change in distance:
∆d=d2−d1=0.008−0.006=0.002m
Calculate the change in area:
∆A=2×0.08×0.002=3.2×10−4m2
The work done (energy needed) is given by:
W=T∆A
Here, surface tension T=0.07Nm−1
So,
‌W=0.07×3.2×10−4=0.224×10−4J
‌W=22.4×10−6J=22.4µJ