ok.........but still i am not convinced if u get a better explanation do tell me

u can com to know by drawing lewis dot structures

no i dont agree wid resin see guys refractive index is always comparitive i.e with respect to other media so how is it possible to compare it wid air then add up????really confused

ya i too think so.........anyways thanx 4 helping me out

ya i think you r right i dunno how cud i go wrong with this ...... so do u say the given ans is wrong ?????

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yup u r perfectly correct thats wat i also did

1/f=(1.7-1)(-1/12.5-1/12.5)

1/f=-0.112

f=-8.29cm

thanx guys

can u pls explain the 2nd eqn??

nope the ans is wrong....the given ans is -31.25 but i am getting -8.29

an iron casting consists of cavities it wieghs 6000N in air and 4000N in water.the density of iron is 7.8g/cm3 find the volume occupied by the cavities

 Two similar plano convex lens are placed with their convex surfaces in contact and the space between them is filled with a liquid of refractive index 1.7, as shown in figure. The focal length of plano convex lens is 25 cm and radius of

curvature of the curved surface is 12.5 cm and is made of glass of refractive index 1.5. Find the focal length of the combination.

i wud give it a 7

according to me bsnl

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