KCET 2018 Physics Solved Paper

Given, first overtone frequency of closed pipe of length l1=2nd harmonic frequency of on open pipe of length l2
Now, first overtone frequency of close pipe

3u

4l1

2nd harmonic frequency of open pipe =

2u

2l2

∴‌

3u

4l1

=‌

2u

2l1

On rearranging, we get
‌

l1

l2

=‌

3u

4

×‌

1

u

=‌

3

4

Therefore, ratio is

l1

l2

=

3

4

.