1) Explain what is meant by the power of a lens? A converging lens of focal length 20cm, forms a real image twice the size of the object. Calculate: i) the power of the lens;
ii) the position of the image.
2) Explain the following terms: reverberation and echo.
3) Explain why sound cannot be polarized.

The sound level near a noisy air conditioner is 70 db. if two such units operate side by side, the sound level near the, would bea. 70dbb. 73 dbc. 105 dbd 140 db

Which of the following statement is false

In a game of pool, ball a is moving with a velocity v0 of magnitude v0 = 15 ft/s when it strikes balls b and c, which are at rest and aligned as shown. knowing that after the collision the three balls move in the directions indicated and assuming frictionless surfaces and perfectly elastic impact (that is, conservation of energy), determine the magnitudes of the velocities va, vb, and vc.