Coin battery

Materials:

A small box of coins (quarters, dimes and nickels)

Saturated potassium chloride (200mL)

Filter paper strips (>100)

Voltage meters (5-10)

Paper towels

Goggles and gloves

Ask the students about batteries in daily life

Explain the function and usage of voltage meter

Explain why the stack of coins can produce electronic current

a. Soak the filter paper strips in saturated potassium chloride.

b. Stack two pile of coins with various combination.

c. Put the two piles together with the filter paper in between.

d. Measure the voltage of the whole stack using a voltage meter.

e. Repeat to get the highest voltage value by changing the order and combination of coins.

a. Make sure all the voltage meters are working before use. If not, change the battery.

b. Make sure the alligator clip from the voltage meter has a clean metal surface. If not, use sand paper to remove the rust.