A combination of two thin lenses in contact behave as converging lens of focal length 80 cm if one of the lense is convrging lens of focal length 20 cm, the power of other lens will be
Explanation.
f= focul length of combination of two lenses
f1= focul length of ist lens
f2= focul length of 2nd lens
As 1/f =1/f1 + 1/f2
1/80 = 1/20 + 1/f2
1/f2 = 1/80 - 1/20
f2 = -26.66cm
= -0.266 m
As Power of lens P= 1/f (where f will be in meters)
So
P=1/-0.266
= -3.75D
Showing posts with label Numericals. Show all posts
Showing posts with label Numericals. Show all posts
Friday 29 August 2014
Some MCQs of Physics and Chemistry.
Q1)when the aircraft concorde is moving in horizontal plane at const speed 650 m/s its turning circle has radius of 80 km wat is ratio of centripetal force to the weight of air craft?
Ans.
Q2)when 0.24 gm of magnesium is reacted with excess HCl what volume of gas librated at RTP
Ans.
Q3)In mixture of NO and CO2 initialy containing 4 mol of NO and 0.9 mol of CO2 reaction ocur acording to NO+CO2>NO2+CO at eq 0.1 mol of CO2 was presnt what is Kc
Ans.
Q4)a box of mas m =6 kg slid with speed v=4 m/s acros frictionless flor it sudenly explodes into 2 pieces one piece with mass m1 =2kg moves in same direction with speed v1=8 m/s find velocity of 2nd piece
Ans. as momentum before collision= momentum after collision
for m2 ,m=m1+m2 6=2+m2 m2=4kg so 6(4)=2(8)+4(x) 8=4x x=2m/s
Q5)Q2) on groud the gravitational force on satelite is W wat is gravitational force on satelite when at height R/50 where R is radius of earth
Ans. On the ground, the distance (from the centre of the Earth) is R. In orbit, the distance is R+R/50 or (51/50)R. The force is (ETA: inversely) proportional to the square of the distance so the multiplier you want is (50/51)^2 ~=0.96W
Q6)equal weights of methane and hydrogen are mixed in an an empty container at 25 degre centegrad the fraction of total presure exerted by hydrogen is.
Ans. apply mole fraction formula by daltons law of partial pressure
as moles fraction=no of moles of components/no of total moles let no of moles H2= n/2 let no of moles of CH4=n/16 total moles = n/2 + n/16 =9n/16 so mole fraction of pressure exerted byH2= n/2 ÷ 9n/16 = n/2 × 16/9n =8/9 ans
Ans.
Q2)when 0.24 gm of magnesium is reacted with excess HCl what volume of gas librated at RTP
Ans.
Q3)In mixture of NO and CO2 initialy containing 4 mol of NO and 0.9 mol of CO2 reaction ocur acording to NO+CO2>NO2+CO at eq 0.1 mol of CO2 was presnt what is Kc
Ans.
Q4)a box of mas m =6 kg slid with speed v=4 m/s acros frictionless flor it sudenly explodes into 2 pieces one piece with mass m1 =2kg moves in same direction with speed v1=8 m/s find velocity of 2nd piece
Ans. as momentum before collision= momentum after collision
for m2 ,m=m1+m2 6=2+m2 m2=4kg so 6(4)=2(8)+4(x) 8=4x x=2m/s
Q5)Q2) on groud the gravitational force on satelite is W wat is gravitational force on satelite when at height R/50 where R is radius of earth
Ans. On the ground, the distance (from the centre of the Earth) is R. In orbit, the distance is R+R/50 or (51/50)R. The force is (ETA: inversely) proportional to the square of the distance so the multiplier you want is (50/51)^2 ~=0.96W
Q6)equal weights of methane and hydrogen are mixed in an an empty container at 25 degre centegrad the fraction of total presure exerted by hydrogen is.
Ans. apply mole fraction formula by daltons law of partial pressure
as moles fraction=no of moles of components/no of total moles let no of moles H2= n/2 let no of moles of CH4=n/16 total moles = n/2 + n/16 =9n/16 so mole fraction of pressure exerted byH2= n/2 ÷ 9n/16 = n/2 × 16/9n =8/9 ans
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