The goal of this activity is to allow students to apply their knowledge of Ohm’s law to a more intuitive and visual system: water flowing through tubes. The total time for this activity is around 30 minutes. Students are assumed to be familiar Ohm’s law (V/R=I) where V is volts, R is resistance, and I is current, as well as the formula for calculating the resistance of a resistor (R=ρl/A). where p is resistivity in ohms/meter, l is length, A is area of the conductor.
The water/hose analogy for electricity is useful for explaining voltage, current, and power. In general terms, charge is water, voltage is the pressure of water, current is the flow of the water. Power is the total amount of water flowing in given time. You can have a small pipe with high pressure, or a large pipe with low pressure each passing the same amount of water. Increasing the height of the water reservoir increases the potential energy of the water (voltage). Resistance can be explained as the roughness of the width of the pipe.
Complete lesson plan: