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Electricity

99 MCQ questions with answers and explanations · page 2 of 4

Q26. The principle of fuse is-

  1. Achemical effect of electricity
  2. Bmechanical effect of electricity
  3. Cthermal effect of electricity
  4. Dmagnetic effect of electricity
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Answer: C) thermal effect of electricity

Q27. The unit of resistance is-

  1. AAmpere
  2. BCoulomb
  3. CHenry
  4. DOm
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Answer: D) Om

Q28. Fans, bulbs etc. installed in houses are fitted with-

  1. Ain order of rank
  2. Bin mixed order
  3. Cin parallel order
  4. Din any order
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Answer: C) in parallel order

Q29. "The potential difference across the ends of a conductor is directly proportional to the current flowing through it." This law is-

  1. ACoulomb's law
  2. BFaraday's law
  3. CJoule's law
  4. DOhm's law
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Answer: D) Ohm's law

Q30. If the radius of a wire is halved, its resistance-

  1. Awill be half
  2. Bwill double
  3. COne fourth will remain
  4. Dwill be sixteen times
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Answer: D) will be sixteen times

Q31. What does Ohm's law define?

  1. Aresistance
  2. Bonly stream
  3. Cvoltage only
  4. Dboth current and voltage
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Answer: D) both current and voltage

Q32. The SI unit of specific resistance is-

  1. AOm
  2. Bohm-meter
  3. Cohm/meter
  4. Dohm/meter2
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Answer: B) ohm-meter

Q33. The length of a wire is L meters, the wire is stretched to 21 meters; now the resistance of the wire will be-

  1. Adouble the previous
  2. Bfour times the previous
  3. Ca quarter of the first
  4. Dwill remain unchanged
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Answer: A) double the previous

Q34. The electrolyte in a typical dry cell is-

  1. AZinc
  2. Bsulfuric acid
  3. Cammonium chloride
  4. Dmanganese dioxide
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Answer: C) ammonium chloride

Q35. The commonly used safety fuse wire is made of-

  1. Aalloy of tin and nickel
  2. Bfrom an alloy of lead and iron
  3. Calloy of nickel and lead
  4. Dfrom an alloy of tin and lead
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Answer: D) from an alloy of tin and lead

Q36. The electrolyte used in a car battery is—

  1. Ahydrochloric acid
  2. Bsulfuric acid
  3. Cnitric acid
  4. Ddistilled water
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Answer: B) sulfuric acid

Q37. 'Dry cell' is-

  1. Aprimary cell
  2. BSecondary Cell
  3. Ctertiary cell
  4. Dquartile cell
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Answer: A) primary cell

Q38. What is the coating of zinc on iron called?

  1. Agalvanization
  2. Belectroplating
  3. CIonization
  4. DNone of these
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Answer: A) galvanization

Q39. "In the process of electrolysis, the amount of substance liberated at an electrode is directly proportional to the total charge flowing through it. This law is-

  1. AFaraday's first law of electrolysis
  2. BFaraday's second law of electrolysis
  3. CFaraday's third law of electrolysis
  4. Dnone of these
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Answer: A) Faraday's first law of electrolysis

Q40. "If there is no change in the physical state of a conductor, such as temperature, then the potential difference applied across the conductor is directly proportional to the current flowing through it." This law is---

  1. ACoulomb's law
  2. BOhm's law
  3. CFaraday's law
  4. DKirchhoff's law
Show answer & explanation

Answer: B) Ohm's law

Q41. An electrical fuse wire must have which of the following property sets for general applications?

  1. AThick wire, high melting point alloy, short length
  2. BThick wire, low melting point alloy, greater length
  3. CShort elongation, low melting point alloy, thin wire
  4. DLonger length, lower melting point alloy, thinner wire
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Answer: C) Short elongation, low melting point alloy, thin wire

Q42. 'Faraday's law' is related to-

  1. Aby electrolysis
  2. Bby the pressure of gases
  3. Cby electrical disconnection
  4. Dby electrical propagation
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Answer: A) by electrolysis

Q43. A fuse wire is used for

  1. Atransmit high electric current without causing harm
  2. Bbreak the electric circuit when excessive current flows
  3. Cto protect a person from electric shock
  4. Dnone of these
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Answer: B) break the electric circuit when excessive current flows

Q44. The safety fuse wire used in domestic electrical appliances is made of the metal whose-

  1. Aresistance is low
  2. Bhave a lower melting point
  3. Cthe specific density is low
  4. Dconductivity is low
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Answer: B) have a lower melting point

Q45. A fuse wire is identified by which of these characteristics?

  1. ALowest resistivity and high melting point
  2. BHigh resistivity and high melting point
  3. Chigh resistivity and low melting point
  4. DLowest resistivity and lowest melting point
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Answer: C) high resistivity and low melting point

Q46. A fuse is installed in the electrical supply mesh as a safety device. Which statement is correct regarding electrical fuses?

  1. AIt is connected in parallel with the mains switch
  2. BIt is mainly made of silver alloys.
  3. CIts melting point is low
  4. DIts resistance is very high.
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Answer: C) Its melting point is low

Q47. A fuse wire is used in an electric circuit to

  1. ATo reduce the cost of electrical energy transmission
  2. BTo keep the voltage level constant
  3. CTo prevent excess current from flowing through a circuit
  4. DTo prevent the electrical wire from overheating
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Answer: C) To prevent excess current from flowing through a circuit

Q48. The filament of an electric bulb is made of which element?

  1. ACopper
  2. BIron
  3. Clead
  4. Dtungsten
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Answer: D) tungsten

Q49. When a bulb is broken, a loud noise is produced because-

  1. AAir rapidly enters the vacuum inside the bulb
  2. BThere is explosive gas inside the bulb.
  3. CThe filament of the bulb reacts with air
  4. DThe gas inside the bulb suddenly expands.
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Answer: A) Air rapidly enters the vacuum inside the bulb

Q50. Why is the air completely removed from an electric bulb?

  1. ATo prevent oxidation of tungsten filament
  2. BTo prevent the bulb from bursting
  3. CTo prevent loss of light due to absorption
  4. Dnone of the above
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Answer: A) To prevent oxidation of tungsten filament

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