2. The angle of incident equals the angle of reflection. (----------------------) 3. The incident sound ray, the reflected sound ray and the perpendicular line from the point of incidence on the reflecting surface, all lie on the same plane, Perpendicular to the reflecting surface.
(----------------------)
4. Collection of sound at a point due to its reflection on a concave surface.
(----------------------)
5. An instrument which is used to produce ultrasonic waves to check the presence of fish gathering [shoals]. (----------------------)
[2] Choose the correct answer: 1. -------------waves are used in medical examinations& identification of embryo's sex and his health condition. (Sonic – Infrasonic – Ultrasonic – Sonic& Ultrasonic)
3.Which of the following relationships is used to estimate the depth of sea bed? (d = t xv - V = t/2 x d - t = d/2 x v - d = t/2 x v )
[3] Give reasons: 40