Which defect of vision is correctly matched with its correcting lens?
A. Hypermetropia - Concave lens
B. Myopia - Concave lens
C. Presbyopia - Cylindrical lens
D. Myopia - Convex lens
Answer: Option B
Solution (By JKSSB Mock Tests)
Myopia (near-sightedness) occurs when the image is focused in front of the retina. It is corrected using a concave (diverging) lens. Hypermetropia (far-sightedness) is corrected with a convex (converging) lens. Astigmatism is corrected with a cylindrical lens. Presbyopia is usually corrected with bifocal lenses.
Explanation:
Seconds pendulum has time period of 2 seconds (1 s for half swing). Frequency f = 1/T = 1/2 = 0.5 Hz. Length about 99.4 cm on Earth. Not exactly 1 m.
Explanation:
Time period T = 1/f = 1/200 = 0.005 s = 5 ms. Frequency is number of cycles per second. Relationship T = 1/f is fundamental. For 200 Hz, period is 5 milliseconds.
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