Current is the rate of charge movement A current exists whenever there is a net movement o electrical charge through a medium I Current amps A Amount of charge Coulombs C time interval seconds S ID: 739745
Download Presentation The PPT/PDF document "Chapter 17-3 Current and Resistance" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Chapter 17-3 Current and ResistanceSlide2
Current is the rate of charge movement
A current exists whenever there is a net movement o electrical charge through a medium.
I = Current (amps, A)
= Amount of charge (Coulombs, C) = time interval (seconds, S)
Slide3
Multiple Choice Practice Problem
The current in a light bulb is 0.835 A. How long does it take for a total charge of 1.67 C to pass through the filament of the bulb?
1.00 s
2.00 s3.00 s4.00 sSlide4
Multiple Choice Practice Problem
The current in a light bulb is 0.835 A. How long does it take for a total charge of 1.67 C to pass through the filament of the bulb?
1.00 s
2.00 s3.00 s4.00 sSlide5
Practice Problems – 10 minutes
In a particular television tube, the beam of current is 60
microamps
(there are 1,000,000 microamps in 1 amp). How long does it take for 3.75x1014 electrons to strike the screen? (Recall an electron has a charge of -1.60x10-19 C).A total charge of 9.0 mC (there are 1000 millicoulombs in 1 Coulomb) passes through a cross-sectional area of nichrome wire in 3.5 s. What is the current in the wire?
How many electrons pass through the cross-sectional area in 10.0 s?
If the number of charges that pass through the cross-sectional area during the given time interval doubles, what is the resulting current?Slide6
Practice Problems – 10 minutes
In a particular television tube, the beam of current is 60
microamps
(there are 1,000,000 microamps in 1 amp). How long does it take for 3.75x1014 electrons to strike the screen? (Recall an electron has a charge of -1.60x10-19 C). (1.0 second)A total charge of 9.0 mC (there are 1000 millicoulombs in 1 Coulomb) passes through a cross-sectional area of nichrome wire in 3.5 s. aWhat is the current in the wire?
(2.6x10
-3
A)
How many electrons pass through the cross-sectional area in 10.0 s
(1.6x10
17
electrons)
If the number of charges that pass through the cross-sectional area during the given time interval doubles, what is the resulting current?
(5.1x10
-3
A)Slide7
Resistance to Current
A 9.0 V battery is capable of producing more current than a 6.0 V battery. However, this will
not always be the case.
If the 9.0 V battery is hooked up to a circuit with a lot of resistance, while the 6.0 V battery is hooked up to a circuit without much resistance, the current could actually be higher in the 6.0 V battery. Slide8
Resistance depends on length, area, material, and temperature.
In order to have as little resistance as possible in a circuit, you would want:
Short cable
Large cross sectional areaExcellent conducting material, such as copper. Low temperatureSlide9Slide10
Length
Vs.Slide11
Cross-Sectional Area
Vs. Slide12
Material
Vs. Slide13
Temperature
Not entirely sure how to illustrate this/couldn’t find the pictures I needed….
As temperature increases, electrons crash into the atoms of the conductor far more often, as the atoms are vibrating around much more. Each collision slows the electrons down and therefore creates more resistance.