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Waves

Question
CBSEENPH11020873
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Two soap bubbles coalesce. It is noticed that whilst joined together, the raddii of the bubbles are a and b where a>b. Then the radius of curvature of the interface between the two bubbles will be

  • a-b

  • a+b

  • ab/(a-b)

  • ab/(a+b)

Solution

C.

ab/(a-b)

According to given figure,

Let the radius of curvature of the common  internal film surface of the double formed by two bubbles be r. Excess of pressure as compared to the atmosphere inside A is (4T/a). In a double bubble, the pressure difference between A and B on either side of the common surface.

 = 4Tb = 4TaThis will be equal to (4T/r)∴ 4Tr = 4Tb -4Taor1r = 1b - 1a = a-bbaor  r = aba-b

Some More Questions From Waves Chapter

When two tuning forks (fork 1 and fork 2) are sounded simultaneously, 4 beats per second are heard. Now, some tape is attached on the prong of the fork 2. When the tuning forks are sounded again, 6 beats per seconds are heard. If the frequency of fork 1 is 200 Hz, then what was the original frequency of fork 2?

The sound waves after being converted into electrical waves are not transmitted as such because

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