A visual physical model for Ohm's Law uses a wood board with ...

[bobbysung]

A visual physical model for Ohm's Law uses a wood board with nails in it and metal balls. The nails in a board represent a fixed amount of electric resistance in a wire.
 
  As the metal balls roll through the nail obstacle course, they run into nails and bounce in various directions. The balls represent the charge carriers in a current; the greater the speed of the balls running through the nails, the greater the current represented. The electric potential energy difference between the ends of the wire is represented by the tilt of the board, because a greater tilt represents a greater difference in gravitational potential energy. Explain how this analogy works.

Question 2

How can a tapered channel (tapchan) work to produce energy? Explain.
 
  What will be an ideal response?

[momo1250]

Answer to Question 1

Ohm's Law says that V = IR. The nails represent a fixed resistance (the number
of nails does not change). Gravitational potential energy is analogous to the electrical
potential energy per unit charge (the potential difference). The greater the tilt, the faster the
balls. Likewise, the greater the potential difference, the greater the electric current. For a
given tilt, we could substitute a board with more nails; this would interfere with the falling of
the balls more, reducing the average speed; in our analogy, it would increase the resistance
and reduce the current. The analogy works very well.

Answer to Question 2

The waves from the ocean at high tide can fill a reservoir, and as the level of the
ocean falls as the tide goes out there is gravitational potential energy that can be converted to
work (or electricity).