Question

20-24 please

2 m Questions 20-21 A standing wave of frequency 20 hertz is set up on a string 2 meters long with nodes at both ends and in the center, as shown above. 20 The speed at which waves propagate the ring is (A) 4 m's (B)20m's C) 5 m/s (D) 10m's (E) 40m's 21. The fundamental frequency of vibration of the string is (A) 10 Hz (B) 2.5 H25H (D) 7.5 H2(E) 1 Hz 22. The critical angle for a transparent material in air is 30. The index of refraction of the material is most nearly (A) 0.33 (B) 0.80 (C) 1.66 (D) 2.0 (E) 0.5 கன 23. An object is placed as shown in the figure above. The center of curvature and the focal point of the reflecting surface are marked. As compared with the object, the image formed by the reflecting surface is (A) upright and larger (B) upright and the same size (C) upright and smaller (D) inverted and larger inverted and smaller 24. When one uses a magnifying glass to read fine print, one uses a (A) converging lens to produce a real image of the point (B) converging lens to produce a virtual image of the print (C) mirror to produce a virtual image of the print (D) diverging lens to produce a real image of the print (E) diverging lens to produce a virtual image of the print

Answer 1

according to HOMEWORKLIB RULES I am allowed to answer only one question and it's four subparts kindly repost remaining subparts