In an organ pipe (may be closed or open ) of `99 cm` length standing wave is set up , whose equation is given by longitudinal displacement.
`xi = (0.1 mm) cos ( 2pi)/(0.8) (y + 1 cm) cos (400) t`where `y` is measured from the top of the tube in `metres` and `t "in" seconds` . Here `1 cm` is the end correction.
Equation of the standing wave in terms of excess pressure is ( take bulk modulus ` = 5 xx 10^(5) N//m^(2)`))
A. `P_(ex) = (125 piN//m^(2)) sin "(2pi)/(80)(y + 1 cm) cos 2pi(400t)`
B. `P_(ex) = (125 piN//m^(2)) cos "(2pi)/(80)(y + 1 cm) sin 2pi(400t)`
C. `P_(ex) = (225 piN//m^(2)) sin "(2pi)/(80)(y + 1 cm) cos 2pi(200t)`
D. `P_(ex) = (225 piN//m^(2)) cos "(2pi)/(80)(y + 1 cm) sin 2pi(200t)`