Resistors

Project Number: 19

Description: Build the circuit shown. Set the meter (M6) to the 50mA setting and the slide switch (S5) to position C. The pivot stand base has 47 ohm and 10K ohm resistors in it. They are used to control the flow of electricity in a circuit. Push the press switch (S2) to measure the 47 ohm resistor; it should be around 50mA. To measure the current through the 10K ohm resistor, set the meter to the 0.5mA setting and the slide switch to position B. Push the press switch to show the current, it should be around 0.4mA. The current is much lower this time, because the 10K ohm is a higher value. The meter has internal resistors, which scale the measurement it makes into the ranges indicated on it. The 10K ohm resistor can be used with it to double the voltage scale to 10V. Keep the slide switch in position B, set the meter to the 5V setting, and push the press switch to measure the battery voltage using a 10V scale (double what you read on the 5V scale).

Snappy: The resistance of a circuit represents how much it resists the electrical pressure (voltage) and limits the flow of electric current. The relationship is Voltage = Current x Resistance. When there is more resistance, less current will flow unless you increase the voltage. Resistance is measured in ohms, or kilo ohms (K ohm, 1000 ohms). What is Resistance? Take your hands and rub them very fast. Your hands should feel warm. The friction between your hands converts your effort into heat. Resistance is the electrical friction between an electric current and the material it is flowing through; it is the loss of energy from electrons as they move through the material.