Physics Help Forum Colour addition/substraction problem (I think)

 Light and Optics Light and Optics Physics Help Forum

 Jun 16th 2009, 09:56 AM #1 Senior Member   Join Date: Mar 2009 Posts: 129 Colour addition/substraction problem (I think) Q: Sandra wore a red and white shirt to a party, at which all the lights were covered with blue filters. In this light, what colour did her shirt appear to be? A: Black and blue How can you tell?! Any help would be greatly appreciated! Thanks in advance!
Jun 16th 2009, 07:04 PM   #2
Senior Member

Join Date: Dec 2008
Location: Udupi, Karnataka, India
Posts: 292
 Originally Posted by s3a Q: Sandra wore a red and white shirt to a party, at which all the lights were covered with blue filters. In this light, what colour did her shirt appear to be? A: Black and blue How can you tell?! Any help would be greatly appreciated! Thanks in advance!
White light is due to addition of primary colors i.e red, blue and green. Blue filter absorbs red and green transmitting blue color.

 Jun 16th 2009, 08:33 PM #3 Junior Member   Join Date: Jun 2009 Posts: 2 hix I don't understand very well. Oh,is there anyone here can help me with this question? 200g of water at 90oC is poured into a cup (mass:210g)at 10oC.The temperature of the water and the cup settles to 75oC. Assuming that no heat escaped into the environment during the process described,what is the specific heat of the cup?From 1-4 below choose the best answer,where the specific heat of water is 4.2 J/g.K? 1)0.22 J/g.K 2)0.71 3)0.92 4)1.2
Jun 16th 2009, 08:55 PM   #4
Senior Member

Join Date: Dec 2008
Location: Udupi, Karnataka, India
Posts: 292
 Originally Posted by aki2510 I don't understand very well. Oh,is there anyone here can help me with this question? 200g of water at 90oC is poured into a cup (mass:210g)at 10oC.The temperature of the water and the cup settles to 75oC. Assuming that no heat escaped into the environment during the process described,what is the specific heat of the cup?From 1-4 below choose the best answer,where the specific heat of water is 4.2 J/g.K? 1)0.22 J/g.K 2)0.71 3)0.92 4)1.2
You have not elaborated what exactly you did not understand.
Regarding the problem, find the heat lost by the hot water. Equate it to heat gained by the cup and the cold water.

 Jun 17th 2009, 05:27 AM #5 Junior Member   Join Date: Jun 2009 Posts: 2 Hix,you didn't explain elaborately.Can you give me the exact key?=> In fact,I'm very bad at physics because when I studied at high school,I almost neglected this subject.=D
 Jun 17th 2009, 09:33 AM #6 Senior Member   Join Date: Mar 2009 Posts: 129 Lol did people forget about me?
Jun 17th 2009, 09:58 AM   #7
Senior Member

Join Date: Dec 2008
Location: Udupi, Karnataka, India
Posts: 292
 Originally Posted by s3a Lol did people forget about me?
When you see this reply on TV, sprinkle a drop of water on the TV screen.
Identify the colors. So the white light isthe mixtur of the three primary colors, red, green and blue.When light passes through blue filter, red and green light are absorbed, But blue is transmitted. So the dress appears blue.

 Thread Tools Display Modes Linear Mode

 Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post kiwiheretic Quantum Physics 5 Jun 19th 2015 05:47 AM ohm Light and Optics 10 Feb 11th 2013 08:32 AM Dorkymichelle Kinematics and Dynamics 3 Feb 2nd 2011 11:39 PM pal_swapan Light and Optics 1 Jun 6th 2009 02:49 AM ohm Light and Optics 1 Apr 22nd 2009 11:50 PM