In the wave equation\( y = 0.5 \sin \dfrac{2\pi}{\lambda}(400t-x) \, \mathrm{m} \)The velocity of the wave will be:
\( 200 \, \mathrm{m/s} \)
\( 200\sqrt{2} \, \mathrm{m/s} \)
\( 400 \, \mathrm{m/s} \)
\( 400\sqrt{2} \, \mathrm{m/s} \)