11Current And Voltage Measurements Multimeters can measure voltage,current and resistance in an electrical circuit.
12It is very importantto choose the correctrange and to connectthe multimeter leadsproperly.
13Ohmic and Non-Ohmic Resistance Ohm’s LawOhmic resistance is constant over a wide range of voltages.Non ohmic resistance varies with voltageSemiconductor diodesOne way valves for electricity17.5, 226, 175
37Electrical Activity In The Heart Muscle action is initiated by electrical activityVoltage pulses cause the heart to beatThese electrical waves travel through the bodyMonitored by electrocardiographsEKG (electrocardiogram)177
38If the atrial and ventricular contractions become irregular, we have fibrillation. Defibrillators can be used to restore the normal heart rhythm17.13
40Cardiac PacemakersCardiac pacemakers may be implanted under the skin and attached with a wire to the right ventricle.A lithium battery is used to charge a capacitor. It discharges 60 times per minute to stimulate the heart beat. If the heart is beating normally, the capacitor is not allowed to charge.
43Cardioverter Defibrillators Implanted Cardioverter Defibrillators (ICDs) can monitor, record, process information, and send corrective signals to the heart.The lithium batteries last 4 – 5 years.Table 17.3 (Defibrillator Properties)
44Electrical Activity In The Brain The brain produces electrical wavesMonitored by electroencephalographsEEG