The waves in which the particles of the medium vibrate in a direction perpendicular to the direction of wave motion are known as:

Which of the following waves are not of the transverse type?

Given below are some examples of wave motion. State in each case if the wave motion is transverse,longitudinal or a combination of both:
$(a)$ Motion of a kink in a longitudinal spring produced by displacing one end of the spring sideways.
$(b)$ Waves produced in a cylinder containing a liquid by moving its piston back and forth.
$(c)$ Waves produced by a motorboat sailing in water.
$(d)$ Ultrasonic waves in air produced by a vibrating quartz crystal.

What are called waves? Mention their importance.

Explain reflection and refraction of waves.

$A$ transverse wave travels along the $x$-axis. The particles of the medium move