Go Back   Physics Help Forum > High School and Pre-University Physics Help > Electricity and Magnetism

Electricity and Magnetism Electricity and Magnetism Physics Help Forum

Reply
 
LinkBack Thread Tools Display Modes
Old Apr 15th 2009, 02:25 AM   #1
Junior Member
 
helloying's Avatar
 
Join Date: Aug 2008
Location: Singapore
Posts: 17
circuit

explain to me please. thank you very much
Attached Thumbnails
circuit-img010.jpg  
helloying is offline   Reply With Quote
Old Apr 15th 2009, 04:01 AM   #2
Physics Team
 
Join Date: Feb 2009
Posts: 1,425
L1 will not light up, as when the switch is closed the two terminals of the lamp are shorted, so there will be no potential difference across them to drive any current thru it .The current flows thru the switch instead.
Now the only resistance in the circuit is that of the second lamp while earlier there was that of L1 also. Since the resistance is lower, a greater current flows from ohms law. So L2 is brighter.
physicsquest is offline   Reply With Quote
Old Apr 15th 2009, 04:08 AM   #3
Physics Team
 
Join Date: Feb 2009
Posts: 1,425
The three 5 ohm resistors are in parallel so their effective resistance Re will be given by
1/ Re = 1/5 + 1/5 + 1/5 or, Re = 5 / 3. The current flowing in the circuit is 3 A.
So by ohmís law, V = I x Re = 3 x 5/3 = 5 V.
physicsquest is offline   Reply With Quote
Reply

  Physics Help Forum > High School and Pre-University Physics Help > Electricity and Magnetism

Tags
circuit



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
RCL circuit help. rcmango Electricity and Magnetism 0 Aug 16th 2011 01:40 AM
circuit missyc8 Electricity and Magnetism 3 Sep 30th 2009 09:19 AM
RC circuit tribble1 Advanced Electricity and Magnetism 1 Mar 22nd 2009 08:18 PM
Circuit dp88 Advanced Electricity and Magnetism 2 Feb 7th 2009 07:34 AM
RC circuit karnold9 Advanced Electricity and Magnetism 3 Sep 26th 2008 07:50 PM


Facebook Twitter Google+ RSS Feed