Does anyone know the answer to this question??
Barometers have long been used to predict the weather. Jay and Jeff were responsible for recording the class weather data each day in March. This particular morning, they tapped the barometer and noticed that the indicator needle did not move. What clue did the barometer give the boys about the up-coming weather?

Figure shows a simple cathode-ray tube. a beam of particles, emitted by the cathode, strikes the centre of the screen.a. why the cathode must be heated? b. what is the principal energy change that occurs when the beam strikes the screen? c describe and explain what you would expect if the two deflecting plates g and h were connected to an alternating voltage supply