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Date: 9-11-2020
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MAGNIFICATION
The magnification, also called power and symbolized ×, is the extent to which a telescope makes objects look closer. (Actually, telescopes increase the observed sizes of distant objects, but they do not look closer in terms of perspective.) The magnification is a measure of the factor by which the apparent angular diameter of an object is increased. A 20× telescope makes the Moon, whose disk subtends about 0.5° of arc as observed with the unaided eye, appear 10° of arc in diameter. A 180× telescope makes a crater on the Moon with an angular diameter of only 1 minute of arc (1/60 of a degree) appear 3° across.
Magnification is calculated in terms of the focal lengths of the objective and the eyepiece. If fo is the effective focal length of the of the objective and fe is the focal length of the eyepiece (in the same units as fo), then the magnification factor m is given by this formula:
m = fo /fe
For a given eyepiece, as the effective focal length of the objective increases, the magnification of the telescope also increases. For a given objective, as the effective focal length of the eyepiece increases, the magnification of the telescope decreases.
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اكتشاف تأثير صحي مزدوج لتلوث الهواء على البالغين في منتصف العمر
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زهور برية شائعة لتر ميم الأعصاب التالفة
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موكب أهالي كربلاء يستذكر شهادة الإمام الصادق (عليه السلام)
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العتبة العباسية تستذكر شهادة الإمام الصادق (عليه السلام) بإقامة مجلس عزاء
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أهالي كربلاء يحيون ذكرى شهادة الإمام الصادق (عليه السلام) في مدينة الكاظمية
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شعبة مدارس الكفيل النسوية تعقد اجتماعًا تحضيريًّا لوضع الأسئلة الامتحانية
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