24. Four Wheel Drives biggest drawbacks of the differentially steered robot is that the robot will veer off course ,if one motor is even a wee bit slow.
50. Zinc-carbon battery - Also known as a standard carbon battery, Alkaline battery - Alkaline chemistry is used in common Duracell and Energizer batteries, the electrodes are zinc and manganese-oxide, with an alkaline electrolyte. Lithium-iodide battery - Lithium-iodide chemistry is used in pacemakers and hearing aides because of their long life. Lead-acid battery - Lead-acid chemistry is used in automobiles, the electrodes are made of lead and lead-oxide with a strong acidic electrolyte (rechargeable). Nickel-cadmium battery - The electrodes are nickel-hydroxide and cadmium, with potassium-hydroxide as the electrolyte (rechargeable). Nickel-metal hydride battery - This battery is rapidly replacing nickel-cadmium because it does not suffer from the memory effect that nickel-cadmiums do (rechargeable). Lithium-ion battery - With a very good power-to-weight ratio, this is often found in high-end laptop computers and cell phones (rechargeable). Zinc-air battery - This battery is lightweight and rechargeable. Zinc-mercury oxide battery - This is often used in hearing-aids. Silver-zinc battery - This is used in aeronautical applications because the power-to-weight ratio is good.
57. 1. The iron is hot and can easily damage parts, cause burns, or even start a fire. Keep the soldering iron in its holder when it is not being held. 2. Make sure that there is a damp sponge available used for cleaning off and tinning the tip. 3. Always make sure that the tip is tinned when the iron is on. To tin the iron, clean the tip and wipe it on a damp sponge and then immediately melt some fresh solder onto the tip. 4. A cold solder joint is a joint where an air bubble or other impurity has entered the joint during cooling. Cold solder joints can be identified by their dull and mottled finish. Cold joints are brittle and make poor electrical connection. 5. Do not hold the iron against the joint for an extended period of time (more than 10 seconds), since many electronic components or the printed circuit board itself
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60. TORQUE Torque is the force the motor exerts upon its load. The higher the torque, the larger the load can be and the faster the motor will spin under that load. Reduce the torque, and the motor slows down, straining under the workload. Reduce the torque even more, and the load may prove too demanding for the motor. The motor will stall to a grinding halt, and in doing so eat up current (and put out a lot of heat). Torque is perhaps the most confusing design aspect of motors. At its most basic level, torque is measured by attaching a lever to the end of the motor shaft and a weight or gauge on the end of that lever,