A thin liquid film formed between a U shaped wire and a light slider supports a weight of 1.5×10−2N, as shown in the figure. The length of the slider is 30 cm and its weight negligible. The surface tension of the liquid film is

Here, W=1.5×10−2N, l=30cm=30×10−2mThe force due to surface tension will balance the weight. i.e., F=WA liquid film has two free surfaces. 2SL=W or S=W2LS=1.5×10−22×30×10−2=0.025Nm−1A slider will support the weight when the force of surface tension acting upwards on the slider (= 2S/) balances the downward force due to weight (= W).