A testing device sends a sound pulse from uncured liquid resin into cured solid resin. Measurements show that the wavelength of the pulse in the cured resin is 1.5 times its wavelength in the liquid resin.
Which gives the frequency and speed in the cured resin compared with those in the liquid resin?
frequency 1.5 times; speed 1.5 times
frequency unchanged; speed unchanged
frequency unchanged; speed 1.5 times
frequency 1.5 times; speed unchanged