Physics - Chap 21 after test

• Voltmeter measures voltage
• ammeter measure current
• Voltmeters are connected in PARALLEL with the device being measured
• Ammeters are connected in SERIES with the device being measured
• The heart of most analog meters in a galvanometer
• A galvanometer is an electromechanical measuring instrument for electric current
• 2 crucial characteristics of a galvanometer

  • resistance
  • current sensitivity
• current sensitivity, use v=ir
• small resistance r - shunt resistance
• Null measurements balance voltages so that there is no current flowing through the measuring device
• 2 types of null measurements

  • potentiometer
  • wheatstone bridge
• Potentiometer - a null measurement device for measuring voltages
• wheatstone bridge - a null measurement device used for calculating resistance by balancing potential drops in a circuit
• RC circuit - one that contains a resistor and a capacitor