UPSC General Science :Electricity Notes Part 1

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Today’s Topic : Electricity

Q1. The tail of comet is directed away from the sun due to:

a) The tail of comet always exists in the same orientation.

b) Radiation emitted by sun exerts a radial pressure on the comet. Throwing its tail away from the sun.

c) Comet rotates around the sun, lighter mass of the comet is pushed away due to centrifugal force.

d) As the comet rotates, lighter mass of comet is attracted by stars situated in the direction of its tail.

Ans:    C

Explanation:    Comet is a celestial bodies which moves around the sun. It is made up by gas, dust particles, ice etc. Tail of comet is directed away from the sun due to centrifugal force. Centrifugal force always acts away from the centre when bodies is in circular motion. Example – Tumble -1, Helly, Fcf = M .


Q2. Assertion (A) : Temperature increases when electric curent is passes through metal.

   Reason (R) : Collision of metal atoms with each other produces heat enregy.


a) Both A and R are true but R is not correct explanation of A.

b) A is true but R is false.

c) A is false but R is true

d) Both A and R are true and R is correct explanation of A.

Ans:     D

Explanation:    The heating effect of an electric current is caused by collisions of electrons with atoms of material. In these collisions, the energy of electrons is lost to positive ions. Metals have positive temperature gradient. It resistance increases when temperature increases.

Q3. Which of the following statements are correct about gold ornaments:

1) Cadmium is used as a solder in making gold ornaments

2) KDM in the gold ornaments stand for cadmium.

3) Cadmium is the cause of lung cancer in Artisans and Fabricators

a) 2 and 3

b) 1 and 2

c) 1 and 3

d) All of these.

Ans:     D

Explanation:    KDM stands cadmium. The finish of gold ornament depends upon the quality of its soldering material. Cadmium has been proven to expose artisans and fabricators to lung cancer and other respiratory disorders.

Q4. Consider the following statements:

1) Wavelength or red light is less than radio waves.

2) Frequency is the fundamental quantity of waves.

3) A widely used musical scale called diatonic scale has seven frequencies.

4) The frequency of the not sa (sa) is 256 HZ and that of Ni 512 HZ.

Which of the statements are correct?

a) 1 and 2

b) 2 only

c) 1,2 and 3

d) 1,2,3 and 4

Ans:     C

Explanation:    Radio waves < Micro waves < Infrared < Visible light

  • Frequency is most fundamental quantity
  • The frequency of each swar is different that’s why we can identify

Sa              –           240HZ

Re              –           270 HZ

Q5. Which one of the following types of waves are used in a Night vision apparatus:

a) Radio waves

b) Infrared waves

c) x-rays

d) Micro waves.

Ans:    B

Explanation:    Night vision is the ability to see in a dark environment by biological or technological means. Night vision device is a device containing infrared image intensifier tube in a. rigid casting, commonly used by military forces. It has greater application in film technology like, Night vision filming and photography.

Q6. Indiscriminate disposal of used fluorescent electric lamps causes mercury pollution in the environment why mercury used in manufacture of these lamps?

a) When the lamp is on, the mercury in the lamp causes the emission of UV radiation.

b) A mercury coating on the inside of the lamp make the light bright white.

c) Mercury converts UV light into visible light.

d) None of the above.

Ans:     A

Explanation:    There are two main parts in a CFL (1) the gas filled tube (also called bulb or burner) and the magnetic or electronic ballast. An electrical current from the ballast flows through the gas (mercury vapour) causing it to emit UV light. The UV light excites the phosphorus coating. It emits visible light.

Q7. Which of the followings are correct:

1) Steam at 1000C and boiled water at 1000C contain same amount of heat.

2) Latent heat of vaporisation of water is not equal to the latent heat of fusion of ice.

3) In AC, heat is extracted from the room air at the evaporator coils and is rejected out at the condenser coils.

Which of these statements are correct?

a) 2 and 3

b) 1, 2 and 3

c) Only 2

d) None of these.

Ans:     A

Explanation:    Latent heat of vapourisation of water is greater than latent heat of fusion of ice.

Lf (ice) = 80 cal/g

Lv (water) = 536 cal/g

Q8. When water will be heated from 00C to 100C , then volume:

a) Increases

b) Decreases

c) Remains constant

d) 1st decreases then increases.

Ans:     D

Explanation:    Generally volume of liquids increases due to beating but water shows reciprocal behaviour between 00C to 40C . At 40C water has minimum volume and maximum density. Density =  .

Q9. Modern Industrial robot is:

1) Programmable                     2) Multifunctional

3) Servo controlled                  4) All of the above

a) 1

b) 2

c) Both 1 and 2

d) All of these.

Ans      D

Explanation:    Robot is an electronic device. It can do different types of work, so it is multifunctional. It is a programmable and servo controlled system.

Q10. Consider the following statements:

A4-wheel vehicle moving in a sharp circular path at high speed, what will happen:

1) Skid outward                                               2) Skid in ward

3) Overturn about its outer wheels                  4) Overturn about its inner wheels

Which of the statements are correct?

a) 2 and 4

b) 1 and 3

c) 1 and 4

d) 2 and 3

Ans:    B

Explanation:    For completing circular motion, centripetal force must be equal to centrifugal force. This centrifugal force is produced by friction between type and road. If the centrifugal force is disturbed then vehicle will skid in outward direction and turn about its outer wheel.

For safely turning =  ≤ μsmg

V≤ μsmg

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