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There is a soap bubble of radius 2.4xx10...

There is a soap bubble of radius `2.4xx10^(-4)m` in air cylinder which is originally at a pressure of `10^(5)(N)/(m^(2))`. The air in the cylinder is now compressed isothermally until the radius of the bubble is halved. (the surface tension of the soap film is `0.08Nm^(-1))`. The pressure of air in the cylinder is found to be `8.08xx10^(n)(N)/(m^(2))`. What is the value of n?

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To solve the problem step by step, we will use the concepts of pressure in a soap bubble and Boyle's law. ### Step 1: Understand the Initial Conditions We have a soap bubble with an initial radius \( r_1 = 2.4 \times 10^{-4} \, \text{m} \) and initial pressure \( P_1 = 10^5 \, \text{N/m}^2 \). The surface tension of the soap film is given as \( \sigma = 0.08 \, \text{N/m} \). ### Step 2: Calculate the Initial Pressure Inside the Bubble The pressure inside the soap bubble can be calculated using the formula: \[ P_{inside} = P_{outside} + \frac{4\sigma}{r} \] Here, \( P_{outside} \) is the atmospheric pressure (initial pressure in the air cylinder), and \( r \) is the radius of the bubble. Substituting the values: \[ P_{inside} = 10^5 + \frac{4 \times 0.08}{2.4 \times 10^{-4}} \] Calculating the term: \[ \frac{4 \times 0.08}{2.4 \times 10^{-4}} = \frac{0.32}{2.4 \times 10^{-4}} \approx 1333.33 \, \text{N/m}^2 \] Thus, \[ P_{inside} = 10^5 + 1333.33 \approx 101333.33 \, \text{N/m}^2 \] ### Step 3: Determine the Final Radius The radius of the bubble is halved, so the final radius \( r_2 \) is: \[ r_2 = \frac{r_1}{2} = \frac{2.4 \times 10^{-4}}{2} = 1.2 \times 10^{-4} \, \text{m} \] ### Step 4: Calculate the Final Pressure Inside the Bubble Using the same formula for the final pressure inside the bubble: \[ P_{inside, final} = P_{outside, final} + \frac{4\sigma}{r_2} \] Let \( P_{outside, final} \) be the final pressure in the air cylinder, which we need to find. Substituting the values: \[ P_{inside, final} = P_{outside, final} + \frac{4 \times 0.08}{1.2 \times 10^{-4}} \] Calculating the term: \[ \frac{4 \times 0.08}{1.2 \times 10^{-4}} = \frac{0.32}{1.2 \times 10^{-4}} \approx 2666.67 \, \text{N/m}^2 \] Thus, \[ P_{inside, final} = P_{outside, final} + 2666.67 \] ### Step 5: Apply Boyle's Law Since the process is isothermal, we can apply Boyle's law: \[ P_1 V_1 = P_2 V_2 \] Where \( V_1 \) is the initial volume and \( V_2 \) is the final volume. The volume of a sphere is given by \( V = \frac{4}{3} \pi r^3 \). The initial volume \( V_1 \) is: \[ V_1 = \frac{4}{3} \pi (2.4 \times 10^{-4})^3 \] The final volume \( V_2 \) is: \[ V_2 = \frac{4}{3} \pi (1.2 \times 10^{-4})^3 = \frac{1}{8} V_1 \] Substituting into Boyle's law: \[ P_1 V_1 = P_2 \left(\frac{1}{8} V_1\right) \] This simplifies to: \[ P_1 = \frac{P_2}{8} \] Thus, \[ P_2 = 8 P_1 \] ### Step 6: Substitute the Values Using \( P_1 = P_{inside} \): \[ P_{outside, final} + 2666.67 = 8 \times 101333.33 \] Calculating \( 8 \times 101333.33 \): \[ 8 \times 101333.33 = 810666.67 \, \text{N/m}^2 \] So, \[ P_{outside, final} + 2666.67 = 810666.67 \] Thus, \[ P_{outside, final} = 810666.67 - 2666.67 = 808000 \, \text{N/m}^2 \] ### Step 7: Express the Final Pressure The final pressure can be expressed as: \[ P_{outside, final} = 8.08 \times 10^5 \, \text{N/m}^2 \] Thus, comparing with the given form \( 8.08 \times 10^n \), we find \( n = 5 \). ### Final Answer The value of \( n \) is: \[ \boxed{5} \]
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