The stationary waves set up on a string have the equation :
`y = ( 2 mm) sin [ (6.28 m^(-1)) x] cos omega t`
The stationary wave is created by two identical waves , of amplitude `A` each , moving in opposite directions along the string . Then :

Options

A. `A = 2 mm`
B. `A = 1 mm`
C. the smallest length of the string is `50 cm`
D. the smallest length of the string is `2 m`

Answer

B, C

Explanation

Comparing with the equation
` y = 2 A sin (( n pi x)/( L)) cos (omega t)` , we have
`2 A = 2 mm` or `A = 1 mm`
and ` (n pi x)/( L) = 6.28 x = 2 pi x`
`L = (n)/(2) m`
for `n = 1 , L = 0.5 m`