UKPCS Science: Conductors, semiconductors and insulators(3) #33

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science (paper #6).

Semiconductor p-n junction diode

If a crystal of p-type material is joined to a crystal of n-type material a p-n junction forms.

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UKPCS Science: Conductors, semiconductors and insulators(1) #31

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science (paper #6).

Classifying materials

Materials can be placed into three groups according to their electrical resistance:

  • conductors
  • semiconductors
  • insulators

Insulators and pure semiconductors have a very high resistance, while conductors have a very low resistance. This difference in conduction is explained by electron bands.

Band theory of conduction Continue reading “UKPCS Science: Conductors, semiconductors and insulators(1) #31”

Target UPSC prelims 2019: Daily MCQs #20

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you daily MCQs.

1. Consider the following statements with respect to National Human Rights Commission (NHRC):
1. It is a statutory and non-constitutional body.
2. The Chairman should be a retired judge of the Supreme Court.
3. The Chairman and members are appointed by the President on the
recommendation of a committee headed by the Prime Minister.
Which of the statement(s) given above is/are
correct?
a. 2 only
b. 1 and 2 only
c. 1 and 3 only
d. 1, 2 and 3
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UKPCS Science: Human Eye(3) #28

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science (paper #6).

Defects of vision and their corrections:

There are three common defects of vision. They are:

1) Myopia (Short-sightedness or Near-sightedness)

2) Hypermetropia (Long-sightedness or Far-sightedness)

3) Presbyopia

Myopia Continue reading “UKPCS Science: Human Eye(3) #28”

Target UPSC prelims 2019: Daily MCQs #19

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you daily MCQs.

1. Consider the following statements with respect to Drone regulation in India:
1. All drones require a Unique Identification Number (UIN) in India.
2. Drones will only be allowed to fly during the day and within the visual line of sight.
Which of the statement(s) given above is/are correct?
a. 1 only
b. 2 only
c. Both 1 and 2
d. Neither 1 nor 2
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UKPCS Science: Human Eye(2) #27

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science (paper #6).

Working of the Eye

The light rays coming from the object enter the eyes through pupil and falls on eye lens. The eye lens then converge the light rays and produce an image of the object on retina which is real and inverted. Retina has large number of light sensitive cells which can generate electrical signals. After the image is formed on the retina it sends electrical signals to the brain and we have a sensation of image. Also, even though the image formed on retina is inverted out mind interprets it as erect.

So, eye lens is the convex lens and retina is the screen of the eye. Continue reading “UKPCS Science: Human Eye(2) #27”

Target UPSC prelims 2019: Daily MCQs #17

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you daily MCQs.

1. Consider the following statements with respect to Bru refugees in India:
1. Large groups of Bru tribes migrated to Tripura after an ethnic clash at
Bangladesh in 1997.
2. Bru refugees are not entitled to vote anywhere in India.
Which of the statement(s) given above is/are
correct?
a. 1 only
b. 2 only
c. Both 1 and 2
d. Neither 1 nor 2
Continue reading “Target UPSC prelims 2019: Daily MCQs #17”

UKPCS Science: Human Eye(1) #26

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science (paper #6).

Parts of eye:

Sclera: The knowledge of eye parts and functions is both useful and interesting. The white part of our eyes is known as sclera. It consists of fibrous tissues. The job of this part it to protect the internal parts of the eye.

Cornea: The transparent tissue through which light enters the eyes is called cornea. It exists in front of the eye. That is why, it looks prominent among different parts of the human eye.

Iris: Iris is made up of muscles which contract or relax in order to adjust the amount of light which enters the eye.

Pupil: There are many interesting facts about the pupil. It is, actually, an aperture controlled by the iris muscles. For instance, when it is dark, the iris muscles relax, causing the pupil to open up wider. Therefore, more light enters the eyes to enable us to see better. On the other hand, the pupil becomes narrow due to the contraction of the iris muscles. It occurs in the presence of excessive light in order to protect the cells of the eyes.

Lens: The lens is present behind the pupil. Light enters the pupil, passes through the lens and is focused on the retina of the eye. The lens is capable of changing its shape in order to help us see near or far off objects. This is about how the human eye works.

Retina: Digging further deeper into the human eye anatomy, you will come across the retina. The retina converts light into electrical signals which are transferred to the brain for processing. The retina contains two types of cells: rods and cones. These cells are sensitive to light. Rods are important for night-time vision when there is little light. On the other hand, cones play an important role in helping us see colors.

Optic Nerve: The optic nerve takes electrical signals from the retina of the eye to the brain.

The Human eye works on the refraction of light through a natural convex lens made up of transparent living material and enables us to see things around us. And the ability to see is called vision, eyesight or drishti. Human eye consists of cornea, iris, pupil, ciliary muscles, eye lens, retina and optical nerve.

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Target UPSC prelims 2019: Daily MCQs #16

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you daily MCQs.

1. Consider the following statements about Western Ghats Ecology Expert Panel:
1. It designated the entire Western Ghats as an Ecologically Sensitive Area (ESA).
2. It divided the area into three zones depending on ecological vulnerability.
Which of the above statements is/are correct?
a. 1 only
b. 2 only
c. Both 1 & 2
d. Neither 1 nor 2
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UKPCS Science: Electrical safety #25

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science (paper #6).

Electricity can be hazardous. Insulation, earthing, fuses and circuit breakers help to protect us from electrical injury. Electrical energy is current multiplied by voltage and time.

  • Insulators are used in electrical equipment to support and separate electrical conductors without allowing current through themselves. Glass, plastic, rubber, air, and wood are used as insulator. They form part of covering of copper wire and restrict the appliance from becoming live.
  • Earthing: It is a part of electrical circuit which is done on initial level in order to connect the electrical system with mass of earth so as to have discharge the electrical energy.

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