What is a Battery?

What is a Battery?

A battery can be defined as an electrochemical device (consisting of one or more electrochemical cells) which can be charged with an electric current and discharged whenever required. Batteries are usually devices that are made up of multiple electrochemical cells that are connected to external inputs and outputs. Batteries are widely employed in order to power small electric devices such as mobile phones, remotes, and flashlights. Historically, the ‘term’ battery has always been used in order to refer to the combination of two or more electrochemical cells. However, the modern definition of the term ‘battery’ is believed to accommodate devices that only feature a single cell.

Batteries are broadly classified into two categories, namely primary batteries and secondary batteries. Primary batteries can only be charged once. When these batteries are completely discharged, they become useless and must be discarded. The most common reason why primary batteries cannot be recharged is that the electrochemical reaction that takes place inside of them is irreversible in nature. It is important to note that primary batteries are also referred to as use-and-throw batteries.

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On the other hand, secondary batteries are the batteries than can be charged and reused for many charging-discharging cycles. The electrochemical reactions that take place inside these batteries are usually reversible in nature. Therefore, secondary batteries are also known as rechargeable batteries. When discharging, the reactants combine to form products, resulting in the flow of electricity. When charging, the flow of electrons into the battery facilitates the reverse reaction, in which the products react to form the reactants.

Important Examples of Batteries

The Lead-Acid Battery

The lead-acid battery is believed to have been invented by the French physicist and inventor Gaston Planté in the year 1859. It is known to be one of the earliest rechargeable batteries. Despite the fact that the lead-acid battery has a very high energy-to-volume ratio and also a very low energy-to-weight ratio, the electrochemical cells in this battery are known to have a fairly large power-to-weight ratio. This can be attributed to their ability to produce strong surge currents. These features of the lead-acid battery, along with its relatively low cost, makes it highly desirable for use in motor vehicles and automobiles in order to provide the high current required to start the engine.

Some key characteristics of the lead-acid battery are:

  • It has the ability to hold an electric charge for up to 3 years.
  • It is ideal for use as an emergency power backup.
  • It is one of the most inexpensive batteries in its output range.

The Nickel-Cadmium Battery (also known as the NiCad Battery)

The nickel-cadmium battery (sometimes referred to as the ‘NiCad’ battery) is a type of rechargeable battery that employs metallic cadmium and nickel oxide hydroxide as the electrodes o the battery. The NiCad battery is known to offer varying discharge rates that are dependent on the size of the battery itself. For example, the discharge rate (maximum) for a typical AA sized cell is approximately equal to 1.8 amperes. On the other hand, the discharge rate for a D size battery can be as high as 3.5 amperes.

The key features of the NiCad battery are listed below.

  • The nickel-cadmium battery features a very fast and even discharge of electrical energy.
  • This type of battery is widely available and is also known to be relatively inexpensive.
  • The NiCad battery can most commonly be found in certain toys and small electronic devices such as TV remotes.

The Lithium-Ion Battery (also known as the LIB Battery)

The lithium-ion battery, often abbreviated to LIB, is a type of secondary battery which is rechargeable. LIBs are known to have many applications in powering electric vehicles and is also known to be used extensively in the aerospace industry.

Within the batteries, during the discharging process, lithium ions are known to pass from the negative electrode to the positive electrode (through an electrolyte ). These lithium ions are also known to travel back when charging. Lithium-ion batteries usually employ an intercalated lithium compound in the positive electrode and usually graphite in the negative electrode as the fuel. Lithium-ion batteries are highly desirable due to their high energy capacity, no memory effect (with the exception of LFP cells), and low self-discharge.

Some key characteristics of LIBs are listed below.

  • The lithium-ion battery is regarded to be one of the most stable and safe batteries. This battery is also known to have a very high energy capacity.
  • LIBs are widely used in mobile phones and portable computers (such as laptops and tablets).
  • This battery has a very slow self-discharge. Furthermore, it is known to have twice the energy capacity of the NiCad battery.

Frequently Asked Questions on Battery Definition

What is the Difference Between Primary Batteries and Secondary Batteries?

Primary batteries are the batteries in which the cell reactions are non-reversible in nature. Therefore, these batteries cannot be recharged. Once they are completely discharged, primary batteries must be thrown away. Secondary batteries, on the other hand, are known to feature reversible cell reactions. Therefore, the reactants in these batteries can be regenerated by supplying an electric current to it. Thus, secondary batteries can be reused over multiple charging and discharging cycles.

What are Wet Cell Batteries?

Wet cell batteries are electric batteries that contain liquid electrolytes. They are also known as vented cells and flooded cells. They are known to be used as learning tools in many electrochemistry labs. It is important to note that both primary and secondary cells can be constructed from electrolytes in the liquid state. Therefore, a wet cell need not necessarily be a primary cell.

What are Dry Cells?

A dry cell is an electrochemical cell in which the electrolyte is a paste. The electrolytes in such cells only contain enough moisture to facilitate the flow of current. Therefore, these cells can be operated in a wide range of orientations without the fear of spillage. Dry cells are widely used in portable electronic devices since they do not contain any free liquid.

MCQ on Battery

1. The mass of an ion liberated at an electrode is directly proportional to the quantity of electricity which passes through the electrolyte”. The above statement is associated with

(A) Webers and Ewings theory

(B) Laplace law

(C) Faraday’s laws of Electrolysis

(D) Gauss’s theorem.

Ans: (C) Faraday’s laws of Electrolysis

2. For all substances Chemical equivalent Electrochemical equivalent

(A) 96500 coulombs

(B) 9650 coulombs

(C) 965 coulombs

(D) 96.5 coulombs.

Ans: (A) 96500 coulombs

3. The capacity of a battery is expressed in terms of

(A). Current rating

(B). Voltage rating

(C). Ampere hour rating

(D). None of the above

Ans: (C). Ampere hour rating

4. The storage battery generally used in electric power station is

(A). Nickel-cadmium battery

(B). Zinc carbon battery

(C). Lead-acid battery

(D). None of the above

Ans: (C). Lead-acid battery

5. Trickle charger of a storage battery helps to

(A). Maintain proper electrolyte level

(B). Increase its reverse capacitor

(C). Prevent sulphation

(D). Keep it fresh and fully charged

Ans: (D). Keep it fresh and fully charged

6. The plates of a lead-acid battery are made of

(A) rolled zinc-copper alloy

(B) cast antimonial lead alloy

(C) perforated nickel-cadmium alloy

(D) pressed antimony bismuth alloy.

Ans: (B) cast antimonial lead alloy

7. In a lead-acid battery, separators are provided

(A) to reduce tendency for polarisation

(B) to facilitate flow of current

(C) to reduce internal resistance

(D) to avoid internal short circuits.

Ans: (D) to avoid internal short circuits.

8. The container of a lead-acid battery is made of

(A) molded hard rubber

(B) ceramics

(C) celluloid

(D) any of the above.

Ans: (D) any of the above.

9. Fillers in a lead-acid battery are provided

(A) to prevent flow of gases

(B) to facilitate flow of gases

(C) to recover acid loss through vapours

(D) all of the above.

Ans: (B) to facilitate flow of gases

10. In the case of a lead-acid battery, during discharging

(A) both anode and cathode become PbSo4

(B) specific gravity of acid increases

(C) voltage of the cells increases

(D) none of the above takes place.

Ans: (A) both anode and cathode become PbSo4

11. On overcharging a battery

(A). It will bring about chemical change inactive materials

(B). It will increase the capacity of the battery

(C). It will raise the specific gravity of the electrolyte

(D). None of the above

Ans: (D). None of the above

12. Battery charging equipment is generally installed

(A). In well ventilated location

(B). In clean and dry place

(C). As near as practical to the battery being charged

(D). In location having all above features

Ans: (D). In location having all above features

13. Batteries are charged by

(A). Rectifiers

(B). Engine generator sets

(C). Motor generator sets

(D). Any of the above

Ans: (D). Any of the above

14. Battery container should be acid resistance therefore it is made up of

(A).Glass

(B). Plastic

(C). Wood

(D). All of the above

Ans: (D). All of the above

15. In a lead acid battery, during charging

(A) anode becomes whitish in colour

(B) voltage drops

(C) specific gravity of acid increases

(D) the cell gives out energy.

Ans:  (C) specific gravity of acid increases

16. The condition of a fully charged lead acid battery can be ascertained by

(A) voltage

(B) specific gravity of electrolyte

(C) gassing

(D) any of the above.

Ans: (D) any of the above.

17. The value of specific gravity of acid when a lead acid battery is fully charged is

(A) 1.285

(B) 2.185

(C) 2.585

(D) 2.9585.

Ans: (A) 1.285

18. The active materials on the positive and negative plates of a fully charged lead acid battery are

(A) pure lead and lead oxide

(B) lead peroxide and lead sulphated

(C) lead peroxide and pure lead

(D) lead sulphate and lead oxide.

Ans: (C) lead peroxide and pure lead

19. A floating battery is one

(A) in which battery voltage is equal to charger voltage

(B) in which the current in the circuit is fully supplied by the battery

(C) which gets charged and discharged simultaneously

(D) which supplies current intermittently and also during off cycle gets charged.

Ans: (D) which supplies current intermittently and also during off cycle gets charged.

20. Which cell has the reversible chemical reaction?

(A) Lead acid 

(B) Mercury oxide

(C) Carbon zinc 

(D) Silver oxide.

Ans: (A) Lead acid 

21. Which of the following statements is correct?

(A) In a Voltaic cell, the anode and cathode are carbon and zinc rod respectively

(B) Leclanche cell suffers from local action and polarisation

(C) Dry cell is basically a Leclanche cell

(D) Edison alkali cell is a primary cell.

Ans: (C) Dry cell is basically a Leclanche cell

22. During charging, the electrolyte of a lead acid battery becomes

(A) stronger

(B) weaker

(C) diluted with water

(D) there is no change in electrolyte.

Ans: (A) stronger

23. Two cells are connected in series to form a battery. Their internal resistance is 0.1 0. The internal resistance of the battery will be

(A) 0.05 Ω

(B) 0.1 Ω

(C) 0.20 Ω

(D) 0.4 Ω

Ans: (C) 0.20 Ω

24. On ampere hour basis the efficiency of a lead acid battery is in the range

(A) 90 to 95 percent

(B) 80 to 85 percent

(C) 70 to 75 percent

(D) 60 to 65 percent.

Ans: (A) 90 to 95 percent

25. In an Edison cell, the electrolyte used is

(A) Sodium chloride

(B) Ammonium sulphate

(C) Potassium hydroxide

(D) Hydrochloric acid.

Ans: (C) Potassium hydroxide

26. The life of a lead-acid battery is expected to be

(A) six month

(B) one year

(C) two to five years

(D) ten to fifteen years.

Ans: (C) two to five years

27. Ampere-hour efficiency of the battery is

(A) 60%

(B) 70%

(C) 80%

(D) 90%.

Ans:(D) 90%.

28. Wat hour efficiency of the battery is

(A) 85%

(B) 75%

(C) 70%

(D) 66%.

Ans: (B) 75%

29. Following will happen if the battery charging rate is too high

(A). Excessive gassing will occur

(B). Temperature rise will occur

(C). Bulging and buckling of plates we occur

(D). All of the above

Ans: (D). All of the above

30. Local action in a battery is indicated by

(A). Excessive gassing under load conditions

(B). Excessive drop in the specific gravity of electrolyte even when the sale is on open circuit

(C). Both A and B

(D). None of the above

Ans: (D). None of the above

31. The following indicate that battery on charge has attained full charge

(A). Colour of electrode

(B). Gassing

(C). Specific gravity

(D). All of the above

Ans: (D). All of the above

32. Which of the following statements is not correct?

(A) A primary cell is an electro-chemical cell

(B) After charging, a primary cell can be again put to use

(C) Dry cell is a primary cell

(D) Leclanche cell is used in experiments, where constant supply of current is not needed.

Ans: (B) After charging, a primary cell can be again put to use

33. The indication of the state of charge of a battery is best given by

(A) specific gravity of electrolyte

(B) temperature of electrolyte

(C) colour of electrolyte

(D) level of electrolyte.

Ans: (A) specific gravity of electrolyte

34. Common impurity in battery electrolyte is

(A) sodium chloride

(B) iron

(C) lead sulphate

(D) dust.

Ans: (B) iron

35. Open circuit voltage of a fully charged lead-acid cell is

(A) 1.9 V

(B) 2.0 V

(C) 2.7 V

(D) 2.5 V.

Ans: (C) 2.7 V

36. The capacity of storage battery is expressed as

(A) the number of recharges it can take

(B) time for which it can be used

(C) the number of cells it contains

(D) ampere hour it can deliver.

Ans: (D) ampere hour it can deliver.

37. On walt hour basis the efficiency of a lead acid battery is in the range

(A) 90 to 95 percent 

(B) 80 to 85 percent

(C) 70 to 85 percent 

(D) 60 to 70 percent.

Ans: (C) 70 to 85 percent 

 38. What is the arrangement to get the maximum current in 3 ohm resistance in the case of 24 cells, each of internal resistance 2 ohms?

(A) 12 cells in series with two rows in parallel

(B) 3 cells in series with three rows in parallel

(C) 6 cells in series with four rows in parallel

(D) 4 cells in series with six rows in parallel.

Ans: (C) 6 cells in series with four rows ill parallel

39. Trickle charge is required for

(A) lead acid batteries

(B) nickel iron cells

(C) primary cells

(D) all of the above.

Ans: (D) all of the above.

40. A wet battery cover in case of lead acid battery indicates

(A) excessive gassing during charging

(B) leaky seals at covers

(C) overfilling of the battery

(D) any of the above.

Ans: (D) any of the above.

41. Internal resistance of a battery is due to

(A) resistance of electrolyte

(B) resistance of electrodes

(C) surface contact resistance

(D) all of the above.

Ans: (D) all of the above.

42. The e.m.f. of a storage battery depends upon

(A) size of the electrodes

(B) shape of the cell

(C) nature of electrodes

(D) all of the above.

Ans: (C) nature of electrodes

43. The internal resistance of a dry cell is of the order of

(A) 0.2 to 0.4 ohm

(C) 2 to 5 ohms

(B) 1 to 1.5 ohm

(D) 1 to 15 ohms.

Ans: (A) 0.2 to 0.4 ohm

44. Proper charging rate for lead acid battery is

(A) 1/2 of rated ampere hour capacity

(B) 1/3 of rated ampere hour capacity

(C) 1/4 of rated ampere hour capacity

(D) 1/8 of rated ampere hour capacity.

Ans: (D) 1/8 of rated ampere hour capacity.

45. For a group of cells when internal resistance of the group is equal to the external resistance due to load, the battery will give

(A) maximum voltage

(B) maximum current

(C) maximum energy

(D) maximum ampere-hours.

Ans: (B) maximum current

46. One ampere hour charge is equivalent to

(A) 36 coulombs 

(B) 360 coulombs

(C) 3600 coulombs 

(D) 36000 coulombs.

Ans: (C) 3600 coulombs 

47. When water is added to sulphuric acid

(A) colour of acid changes

(B) lot of heat is generated

(C) water starts boiling

(D) acid particles get separated.

Ans: (B) lots of heat is generated

48. To prevent local action in battery, only …………is used in electrolytes

(A). Pump water

(B). Distilled water

(C). Tap water

(D). Both A and C

Ans: (B). Distilled water

49. Ampere hour capacity of an industrial battery is based on ……….hours discharge rate

(A). 8

(B). 12

(C). 16

(D). 24

Ans: (A). 8

50. A battery of six cells will show a drop of ……..volts from fully charged state to fully discharged state

(A). 1

(B). 1.5

(C). 2.4

(D). 2.9

Ans: (C). 2.4

51. Which of the following battery is used for aircraft?

(A). Lead-acid battery

(B). Nickel-iron battery

(C). Dry cell battery

(D). Silver oxide battery

Ans: B. Nickel-iron battery

52. When two batteries are connected in parallel, it should be ensured that

(A). They have same emf

(B). They have same make

(C). They have same ampere hour capacity

(D). They have identical internal resistance

Ans: A. They have same emf

53. If a battery is to be charged at a much higher rate as compared to normal charging rate, the charging should be restricted to

(A). 95% of the capacity of battery

(B). 80% of the capacity of battery

(C). 55% of the capacity of battery

(D). 35% of the capacity of battery

Ans: (B). 80% of the capacity of battery

54. A floating battery is one

(A). Which gets charged and discharged simultaneously

(B). Which supplies current intermittently and also during off-cycle gets charged

(C). In which battery voltage is equal to charger voltage

(D). In which the current in the circuit is fully supplied by the battery

Ans: (B). Which supplies current intermittently and also during off-cycle gets charged

55. The electro-chemical reactions are not reversible in case of

(A) primary cells only

(B) secondary cells

(C) both primary and secondary cells.

Ans: (A) primary cells only

56. The energy in a lead acid battery is stored in the form of

(A) electrostatic charge

(B) Don-flowing current

(C) chemical energy

(D) nuclear energy.

Ans: (C) chemical energy

57. The electrolyte in a Leclanche cell is

(A) dilute hydrochloric acid

(B) aqueous solution of ammonium chloride

(C) pyrogallic acid

(D) lead stearate.

Ans: (B) aqueous solution of ammonium chloride

58. The electrode for a battery must be

(A) a good conductor of electricity

B) a bad conductor of electricity

(C) a semi-conductor

(D) an insulator

Ans: (A) a good conductor of electricity

59. For a discharged lead-acid battery, the specific gravity of the acid is

(A) 0.9

(B) 1.0

(C) 1.12

(D) 1.3.

Ans: (C) 1.12

60. In a lead accumulator, the plates are placed close to each other, as :

(A) it makes the lead accumulator sturdy

(B) it increases the e.m.f. of the accumulator

(C) it decreases the internal resistance of the accumulator

(D) it increases the life span of the accumulator.

Ans: (C) it decreases the internal resistance of the accumulator

61. Even when not in use, the self-discharge of a battery occurs at the rate of

(A) 0.5 to 1% of rated capacity per hour

(B) 0.5 to 1% of rated capacity per day

(C) 0.5 to 1% of rated capacity per week

(D) 0.5 to 1% of rated capacity per month.

Ans: (B) 0.5 to 1% of rated capacity per day

62. The specific gravity of acid is checked with the help of a

(A) hygrometer

(B) lactometer

(C) hydrometer

(D) cell tester

Ans: (C) hydrometer

63. Which of the following statements is not correct? A lead accumulator of 20-ampere hour can supply

(A) 20 A of current for 20 hours

(B) 1 A of current for 20 hours

(C) 20 A of current for 1 hour

(D) 0.1 A of current for 200 hours.

Ans: (A) 20 A of current for 20 hours

64.  The term trickle charge is associated with

(A) dry cells

(B) silver zinc batteries

(C) lead acid batteries

(D) nickel iron batteries.

Ans: (C) lead acid batteries

65. When the battery is being charged. the terminal voltage decreases with

(A) increasing charging rate

(B) increasing state of charge

(C) increasing temperature

(D) all of the above.

Ans: (C) increasing temperature

66. When the battery is being discharged, the terminal voltage decreases with

(A) decreasing discharge rate

(B) decreasing state of charge

(C) decreasing temperature

(D) none of the above.

Ans: (A) decreasing discharge rate

67. The ampere hour capacity of a battery used on cars is

(A) 5-10 Ah 

(B) 30 – 60 Ah

(C) 100 – 150 Ah 

(D) 200-250 Ah.

Ans: (B) 30 – 60 Ah

68. The ampere hour capacity of a battery used on trucks is

(A) 5 – 10 Ah 

(B) 30-60 Ah

(C) 100-150 Ah 

(D) 200-250 Ah.

Ans: (C) 100-150 Ah 

69. Which battery is used in aeroplanes?

(A) Dry cell battery

(B) Lead acid battery

(C) Edison cell

(D) None of the above.

Ans: (D) None of the above.

70. Which test is listed to ascertain whether the battery plates are defective or not?

(A) Cadmium test

(B) High discharge test

(C) Open volt test

(D) Specific gravity test.

Ans:(A) Cadmium test 

71. Which of the following is the common voltage of automobile batteries

(A)2 V

(B) 10 V

(C) 12 V

(D) 25 V.

Ans: (A)2 V

72. Cells are connected in parallel to

(A) increase the voltage output

(B) increase the internal resistance

(C) decrease the current capacity

(D) Increase the current capacity 

Ans: (D) Increase the current capacity 

73. A constant voltage source has

(A) low internal resistance

(B) high internal resistance

(C) minimum efficiency

(D) minimum current capacity.

Ans: (A) low internal resistance

74. Which of the following is false?

(A) A carbon-zinc cell has unlimited self life

(B) A lead-acid cell can be recharged

(C) A storage cell has an irreverse chemical reaction

(D) A primary cell has an irreversi chemical reaction.

Ans: (A) A carbon-zinc cell has unlimited self life

75. The current in a chemical cell is a movement of

(A) positive hole charges

(B) positive ions only

(C) negative ions only

(D) positive and negative ions.

Ans: (D) positive and negative ions.

76. Cells are connected in series to

(A) increase the voltage output

(B) decrease the voltage output

(C) decrease the internal resistance

(D) increase the current capacity.

Ans: (A) increase the voltage output

77. Which of the following is a dry storage cell?

(A) Mercury cell

(B) Nickel-cadmium cell

(C) Carbon-zinc cell

(D) Edison cell.

Ans: (B) Nickel-cadmium cell

78. Two batteries having unequal emf

(A) cannot be connected in parallel

(B) cannot be connected in series

(C) can be connected in series only

(D) maybe connected in parallel or series.

Ans: (C) can be connected in series only

79. The terminal voltage when the battery is being charged decreases with

(A). Increasing temperature

(B). Increasing charging rate

(C). Increasing stage of charge

(D). All of the above

Ans: (A). Increasing temperature

80. Which test is used to ascertain whether the battery plates are defective or not ?

(A). Open volt test

(B). Cadmium test

(C). High discharge test

(D). Specific gravity test

Ans: (B). Cadmium test

81. The electrode for a battery must be

(A). A semiconductor

(B). An insulator

(C). A good conductor of electricity

(D). A bad conductor of electricity

Ans: (C). A good conductor of electricity

82. Cells are connected in series in order to

(A). Increase the voltage rating

(B). Increase the current rating

(C). Increase the life of the cells

(D). None of the above

Ans: (A). Increase the voltage rating

83. Which of the following material is used in solar cells?

(A) Silicon

(B) Barium

(C) Selenium 

(D) Silver

Ans: (A) Silicon

84. The efficiency of a solar cell can be expected in the range

(A) 10 to 15 percent 

(B) 25 to 35 percent

(C) 45 to 60 percent 

(D) 70 to 85 percent.

Ans: (A) 10 to 15 percent 

85. The output voltage of a silver oxide cell is

(A) 1.1 volt

(B) 1.2 volt

(C) 1.5 volt

(D) 1.71 volt.

Ans: (C) 1.5 volt

86. In a lithium cell the positive electrode is made of

(A) zinc dust

(B) stainless steel

(C) spongy iron 

(D) carbon.

Ans: (D) carbon.

87. Which efficiency of a battery is more than the remaining ?

(A) Watt hour efficiency

(B) Ampere hour efficiency

(C) Overall efficiency

(D) (A), (B) and (C) above have the same value.

Ans: (B) Ampere hour efficiency

88. While comparing alkaline batteries, with lead acid batteries, which one of the following can be cited as the advantage of the former over the latter?

(A) Low initial cost

(B) Electrical robustness

(C) High output voltage

(D) All of the above.

Ans:(B) Electrical robustness 

89. A fuel cell converts ……….. energy into electrical energy

(A) chemical

(B) mechanical

(C) solar

(D) magnetic.

Ans: (A) chemical

90. In a lead-acid cell, hydrogen is liberated at 

(A) negative plate

(B) positive plate

(C) both negative and positive plates

(D) none of the plates.

Ans: (A) negative plate

91. In a lead-acid cell PbSO4 is formed during

(A) charging only

(B) discharging only

(C) both during charging as well discharging

(D) neither during discharging nor charging

Ans: (B) discharging only

92. To keep the terminals of a lead-acid storage battery free from corrosion, it is advisable to

(A) apply petroleum jelly

(B) dini boles on the terminal top

(C) keep the electrolyte level low

(D) charge the battery at frequent intervals.

Ans: (A) apply petroleum jelly

93. Five 2 V cells are connected in parallel. The output voltage is

(A). 1 V

(B). 1.5 V

(C). 1.75 V

(D). 2 V

Ans: (D). 2 V

94. A dead storage battery can be revived by

(A). Adding distilled water

(B). Adding so-called battery restorer

(C). A dose of H2SO4

(D). None of the above

Ans: (D). None of the above

95. The open-circuit voltage of any storage cell depends wholly upon

(A). Its chemical constituents

(B). On the strength of its electrolyte

(C). Its temperature

(D). All of the above

Ans: (D). All of the above

96. Each cell has a vent cap

(A). To allow gases out when the cell is on charge

(B). To add water to the cell if needed

(C). To check the level of electrolyte

(D). To do all above functions

Ans: (D). To do all above functions

97. Cell short circuit results in

(A). Low specific gravity electrolyte

(B). Abnormal high-temperature

(C). Reduced gassing on charge

(D). All of the above

Ans: (D). All of the above

98. Internal resistance of a cell is reduced to by

(A). Using vent plug to permit gas formed during discharge

(B). Increasing the plate area

(C). Putting plates very close together

(D). All of the above

Ans: (D). All of the above

99. When cells are connected in parallel grouping, then 

(A) Current-capacity decreases

(B) Current capacity increases

(C) EMF increases

(D) EMF decreases.

Ans: (B) Current capacity increases

100. For cadmium plating cathode current density is usually restricted to

(A) 1 to 3 amperes/ dm2

(B) 5 to 10 amperes / dm2

(C) 10 to 15 amperes/dm2

(D) 25 amperes/dm2

Ans: (A) 1 to 3 amperes/ dm2

116. Self Life of a small dry cell is

(A). Equal to that of larger dry cell

(B). Less than that of large dry cell

(C). More than that of large dry cell

(D). None of the above

Ans: B. Less than that of large dry cell

117. The current in a chemical cell is a movement of

(A). Positive ions only

(B). Positive and negative ions

(C). Negative ions only

(D). Positive hole charges

Ans: (B). Positive and negative ions

118. Which of the following primary cells has the lowest voltage?

(A). Lithium

(B). Zinc chloride

(C). Mercury

(D). Carbon zinc

Ans: (C). Mercury

119. Which of the following primary cells has the highest voltage ?

(A). Manganese-alkaline

(B). Carbon-zinc

(C). Lithium

(D). Mercury

Ans: (C). Lithium

120. Short-circuiting of a cell may be caused by

(A). Buckling of plates

(B). Faulty separators

(C). Lead particles forming circuit between positive and negative plates

(D). Any of the above

Ans: (D). Any of the above

121. During electroplating the weight of substance deposited depends on

(A) quantity of electricity

(B) shape of the article

(C) room temperature

(D) atmospheric humidity.

Ans: (A) quantity of electricity

122. During electroplating, the amounts of different substances liberated by same quantity of electricity are proportional to their

(A) atomic weights 

(B) atomic numbers

(C) chemical equivalents

(D) valency.

Ans: (C) chemical equivalents

123. Electro-chemical equivalent is usually expressed in

(A) milligrams per volt

(B) milligrams per KVA

(C) milligrams per kW

(D) milligrams per coulomb.

Ans: (D) milligrams per coulomb.

124. Current efficiency in electroplating usually

(A) 99 %

(B) 90 to 98 %

(C) 70 to 80 %

(D) 50 to 60 % 

Ans: (B) 90 to 98 %

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