Question
Which one of the following lenses should be used to
correct the defect of astigmatism?Solution
Astigmatism is an optical defect in which vision is blurred due to the inability of the optics of the eye to focus a point object into a sharp focused image on the retina. This may be due to an irregular or toric curvature of the cornea or lens. The two types of astigmatism are regular and irregular. Irregular astigmatism is often caused by a corneal scar or scattering in the crystalline lens, and cannot be corrected by standard spectacle lenses, but can be corrected by contact lenses.
Pipes ‘A’ and ‘B’ together can fill a tank in 18 hours, while pipe ‘B’ alone can fill it in 36 hours. If pipe ‘C’ takes 12 hours less th...
An inlet pipe can fill a tank in 10 hours, whereas an outlet pipe can empty the same tank in 25 hours. Find the time taken by two such inlet pipes and o...
Two pipes A and B can fill a tank in 24 min and 32 min respectively. If both the pipes are opened simultaneously, after how much time B should be closed...
Pipe 'A' alone takes 16 minutes to fill half of the empty tank. Pipe 'B' is thrice as efficient as pipe 'A'. Find the percentage of the tank filled by ...
Tap A can fill a tank in 9 hours. Tap B can fill 37.5% part of the same tank in 3 hours, whereas Tap C can alone empty a tank in ‘x’ hours. 2/5 part...
Pipes X and Y can independently fill a tank in 80 minutes and 90 minutes respectively, while pipes X and Z together take 3 hours to fill the same tank. ...
The efficiencies of two inlet pipes, 'P' and 'Q', are in the ratio of 3:5, respectively. When both pipes are open together, the tank is filled in 16 hou...
Pipes 'E' and 'F' can fill a tank in 20 and 25 minutes respectively. Both are opened together. A leak develops after half of the tank is filled, which r...
Pipe ‘A’ fills a tank in 16 hours. Pipe ‘B’ empties the same in 32 hours. If both are opened together, how much time will it take to fill 50% o...
The time taken by pipe B3 alone to fill an empty tank completely is half of the time taken by pipe B1 alone to fill the same tank completely. Pipe B2 al...
