Which one of the following is the correct sequence of passage of light in a compound microscope?
- A.Condenser-Objective lens-Eyepiece-Body tube
- B.Objective lens-Condenser-Body tube-Eyepiece
- C.Condenser-Objective lens-Body tube-Eyepiece
- D.Eyepiece-Objective lens-Body tube-Mirror
Correct answer
Explanation
The correct answer is C, Condenser-Objective lens-Body tube-Eyepiece. Light passes through the condenser to the specimen, is picked up by the objective lens, travels up the body tube and reaches the eye through the eyepiece.
In a compound microscope the mirror or lamp at the base sends light up into the condenser, which focuses it on the slide placed on the stage. The objective lens, close to the specimen, forms a real, inverted and magnified image inside the body tube. The eyepiece at the top of the tube then magnifies this image again, so the total magnification is the product of the two, for example 10x eyepiece and 40x objective give 400x.
Option A is wrong because the eyepiece sits at the top of the body tube, so light reaches it last. Option B is wrong because the condenser lies below the stage and light reaches it before the objective. Option D is wrong because it runs the path backwards; the mirror is where light starts, not where it ends.
Exam tip: light path = mirror, condenser, specimen, objective, body tube, eyepiece; magnification = objective x eyepiece.
Practice Questions
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- A.Urea is produced in liver.
- B.Urea is produced in blood.
- C.Urea is produced from digestion of starch.
- D.Urea is produced in lung and kidney.
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Read the full explanation →Which one of the following statements regarding haemoglobin is correct?
- A.Haemoglobin present in RBC can carry only oxygen but not carbon dioxide.
- B.Haemoglobin of RBC can carry both oxygen and carbon dioxide.
- C.Haemoglobin of RBC can carry only carbon dioxide.
- D.Haemoglobin is only used for blood clotting and not for carrying gases.
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Read the full explanation →Which one of the following statements regarding histone proteins is correct?
- A.Histones are proteins that are present in mitochondrial membrane.
- B.Histones are proteins that are present in nucleus in association with DNA.
- C.Histones are proteins associated with lipids in the cytosol.
- D.Histones are proteins associated with carbohydrates in the cytosol.
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They are the proteins around which DNA winds to form chromatin in the nucleus of eukaryotic cells. Histones are small basic proteins, rich in the positively charged amino acids lysine and arginine, which attract the negatively charged phosphate groups of DNA.
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- A.only proportional region of the stress-strain curve
- B.entire stress-strain curve
- C.entire elastic region of the stress-strain curve
- D.elastic as well as plastic region of the stress-strain curve
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Read the full explanation →What is a constellation?
- A.A particular pattern of equidistant stars from the earth in the sky
- B.A particular pattern of stars that may not be equidistant from the earth in the sky
- C.A particular pattern of planets of our solar system in the sky
- D.A particular pattern of stars, planets and satellites in the sky due to their position in the space
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