UPSC General Science : Electro Magnetic Notes Part 2

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Today’s Topic: Electro Magnetic

Q1. Consider the following statements and select correct code:

1) The hammering decreasing the agitation of the molecules.

2) When a magnet heated and hammered it magnetised is destroyed.

a) 1and 2 are correct

b) Only 1 correct

c) Only 2 correct

d) 1 and 2 both are incorrect.

Ans:     C

Explanation:    When a magnetic is heated, the agitation of its molecules increases not decreases. The hammering further increasing it and when we hammered magnet the magnetised is destroyed.

Q2. One of the following statement is incorrect:

a) Human eyes respond best in yellow light.

b) The largest wavelength we can see is deep red about 700nm.

c) White light is a mixture of all the colour in visible spectrum.

d) None of the above.

Ans:     A

Explanation:    Except option (a) all of the above option is correct because human eyes is respond best to green light at 550 nm which is approximately the brightest colour in sunlight at the surface of the earth.

Q3. Consider the following statement and select the correct code:

1) All electromagnetic wave have the same velocity in space.

2) Light wave and radio wave are actually electromagnetic wave which differ only in their frequencies.

a) Both 1 and 2 correct

b) Only 1 correct

c) Both 1 and 2 are incorrect

d) Only 2 correct

Ans:     A

Explanation:    All electromagnetic wave have equal velocity in space. Light wave and radio wave may seem to be very different. But actually they are the same thing. The electromagnetic wave have equal velocity but different frequencies. The velocity of electromagnetic wave is 3 x 10 10cm/sec.

Q4. The equation Zn + 2nH4Cl-2NH3 + ZnCl2=2H=Ze represents the equation for which one of the following cell:

a) Leclanche cell

b) Dry cell

c) Standard cell

d) None of the above.

Ans:     A

Explanation:    In Leclanche cell carbon rod and zinc rod act as positive and negative poles respectively. The solution is that of ammonium chloride. So from the above option (a) is relates with question.

Q5. Which among the following is a poor conductor of electricity:

a) Carbon

b) Dry wood

c) Paraffin

d) None of these.

Ans:     B

Explanation:    Dry wood, moist wood, leather, moist earth, tap water, rubber, clean water, etc. Are poor conductor of current. Glass, mica, paraffin, rubber and amber are insulator.

Q6. Two resistance are joined in parallel whose resistant is 6/5 ohms. One of the resistance wire is broken and resistance becomes 2 ohms. The resistance in ohms of the wire that broken is:

a) 4

b) 9/5

c) 3

d) 6/5

Ans:     C


Here we noted that


So X=3 ohms.

Q7. IF a train moving very fast with the velocity of light, its length would be:

a) Half of the original

b) Zero

c) Infinite

d) Unchanged

Ans:    B

Explanation:    We noted that

Q8. If a magnet is left to itself which one of the following option would happen:

a) Its magnetic effect would first get strengthened and then weekend.

b) There would be no change in its magnetic properties.

c) Its magnetic effect would be unchanged.

d) It would have demagnetizing effect.

Ans:     D


If a magnet left to itself due to indication of their own poles through the material of the magnets. So option (d) is correct.

Q9. Which one of the following is spectrum of carbon monoxide:

a) Continuous spectrum

b) Bad spectrum

c) Fluorescence spectrum

d) None of the above.

Ans:    B

Explanation:    Light emitted by chemical compounds in vapour states give Band spectrum. Therefore, spectrum of carbon monoxide will be Band spectrum. So in above option (b) is correct about spectrum of carbon monoxides.

Q10. The same notes is being played on sitar and veena. In which of the following they would differ:

a) Pitch

b) Quality

c) Both of the true

d) None of the true.

Ans:     B

Explanation:    From the above option (b) is correct. As sitar and are being played for the same note, frequency is the same but the sound produced from the both are different tunes. Therefore they different in quality.