Transcript Lecture 5
Admin: • Discussion sections start tommorrow. • Very useful prep for tests. • You are expected to attend. • From the lab TAs: try and complete your lab reports before leaving the lab (or soon after). • Register for MasteringPhysics • www.masteringphysics.com • Course ID: MPHOLDER67874 • 118/132 Registered • First graded assignment is posted. • Due Monday 23rd Copyright © 2009 Pearson Education, Inc. Resistors in Series and in Parallel How much current is drawn from the battery shown? Copyright © 2009 Pearson Education, Inc. Resistors in Series and in Parallel Example: Current in one branch. What is the current through the 500-Ω resistor shown? (Note: This is the same circuit as in the previous problem.) The total current in the circuit was found to be 17 mA. Copyright © 2009 Pearson Education, Inc. Resistors in Series and in Parallel Example: Bulb brightness in a circuit. The circuit shown has three identical lightbulbs, each of resistance R. (a) When switch S is closed, how will the brightness of bulbs A and B compare with that of bulb C? (b) What happens when switch S is opened? No math required! Copyright © 2009 Pearson Education, Inc. Resistors in Series and in Parallel Example : Analyzing a circuit. A 9.0-V battery whose internal resistance r is 0.50 Ω is connected in the circuit shown. (a)How much current is drawn from the battery? (b)What is the terminal voltage of the battery? (c)What is the current in the 6.0-Ω resistor? Copyright © 2009 Pearson Education, Inc. Question on next week’s assignment!! Copyright © 2009 Pearson Education, Inc. Ammeters and Voltmeters An ammeter measures current; a voltmeter measures voltage. Both are based on galvanometers, unless they are digital. Luigi Galvani • current is passed through a coil in a magnetic field • coil experiences a torque proportional to the current. • If the coil's movement is opposed by a spring, then the amount of deflection of a needle attached to the coil is proportional to the current passing through the coil. Copyright © 2009 Pearson Education, Inc.