Integrated Coordinated Science for the 21st Century
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Answers
Physics To Go
- a) Electrical energy.
b) Sound energy.
- It would not have worked very well. Each turn of the coil adds to the back-and-forth force put on the bottom of the cup.
- a) The number of turns in the coil; the distance between the magnet and the coil; the strength of the magnet; the material of the cup.
b) You could look for a thinner material for the bottom of the cup, so it would vibrate more easily. You could increase the number of turns of the coil. You could use finer wire for the coil to reduce the mass you must vibrate. You could mount the magnet more precisely to reduce the distance between the magnet and the coil. You could find a stronger magnet.
- a) Moving the magnet relative to the coil produces a current.
b) If a current flows through coil, it will act like a magnet.
c) The speaker contains a coil placed next to a magnet. When current flows through the coil, it acts like magnet and feels a force from the permanent magnet. Since the current is constantly switching direction (like the vibrating air that originally produced the electrical signal) the force on the coil constantly switches direction, so the cardboard of the speaker vibrates.
d) The microphone contains a coil of wire placed next to a magnet. Sound vibrations move the coil back and forth, which creates a back-and-forth current in the coil.
- a) The light is changing with a particular frequency.
b) Nothing.
c) The light from the flashlight is not changing.
- a) Light.
b) Electricity.
- a) Aim the laser so it shines on the photocell. (You might change the beam direction with mirrors.)
b) The laser, because its beam can go a great distance without spreading out.
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