If You Need A Formula, Just Check Your Watch

No longer do you need to fuss with looking for formulas when you're in the middle of a project and your hands are full. Instead, take a look at your wrist. TechNote Time Watch Co. offers a series of timepieces that feature key equations based on Ohm's Law.

These watches and clocks come with sets of formulas printed on their faces. Two formula sets are available: one style for alternating current, and another for direct current. TechNote Time Watch recommends the ac style for engineers and master electricians and the dc style for students and hobbyists.

Or, completists could take advantage of the HangTime ACDC clip-on watch (see the figure). This model features dc Ohm's Law and power formulas etched onto its flip-down cover. Inside, ac Ohm's Law, power formulas, and a resistor band color chart can be found on the watch's face. Since it has a clip, engineers can latch it anywhere they would need a handy reference. Its Seiko movement and sweep-seconds hand make it an effective timepiece as well.

Prices for the ac and dc versions of the desk and wall clocks range from $24.50 to $37.50. Watches cost from $26.50 to $55, depending on style. The HangTime ACDC clip-on, which features heavy steel construction to ensure durability in the field, comes with a lifetime warranty and costs $60.