Unit 13: Batteries and Other Sources of Electricity

Question 1

What is a voltaic cell?

Answer 1

A voltaic cell converts chemical energy into electrical energy. They are constructed from almost any two unlike metals and an electrolyte of acid, alkali, or salt. Voltaic cells depend on the movement of ions in solution to produce electricity.

Question 2

What factors determine the amount of voltage produced by a cell?

Answer 2

The amount of voltage produced by a cell is determined by the materials from which it is made.

Question 3

What determines the amount of current a cell can provide?

Answer 3

The amount of current a cell can provide is determined by the area of the cell plates.

Question 4

What is a battery?

Answer 4

A battery is a group of cells connected together.

Question 5

What is a primary cell?

Answer 5

A primary cell is a cell that cannot be recharged.

Question 6

What is a secondary cell?

Answer 6

The secondary cell is characterized by the fact that once its stored energy has been depleted, it can be recharged.

Question 7

What material is used as the positive electrode in a zinc-mercury cell?

Answer 7

Mercuric Oxide

Question 8

What is another name for the Leclanché cell?

Answer 8

Carbon-Zinc Cell

Question 9

What is used as the electrolyte in a carbon-zinc cell?

Answer 9

A mixture of ammonium chloride, manganese dioxide, and granulated carbon.

Question 10

What is the advantage of the alkaline cell as compared with the carbon-zinc cell?

Answer 10

The average alkaline cell can supply from three to five times the energy of a carbon-zinc cell, depending on the discharge rate when the cell is being used.

Question 11

What material is used as the positive electrode in an alkaline cell?

Answer 11

Manganese Dioxide

Question 12

How is the A-hr capacity of a lead-acid battery determined?

Answer 12

The ampere-hour rating for lead-acid batteries is determined by measuring the battery’s ability to produce current for a 20-hour period at 80F. A battery with the ability to produce a current of 4 amperes for 20 hours would have a rating of 80 ampere-hours.

Question 13

What device is used to test the specific gravity of a cell?

Answer 13

A hydrometer is a device for measuring the specific gravity of the electrolyte.

Question 14

A 6-V lead-acid battery has an A-hr rating of 180 A-hr. The battery is to be load tested. What should be the test current, and what are the maximum permissible amount and duration of the voltage drop?

Answer 14

The test current will be 540 amperes (180 A x 3), and the voltage should not drop below 4.8 volts (6 V x 0.80) for a period of three minutes.

Question 15

Three 12-V, 100-A-hr batteries are connected in series. What are the output voltage and A-hr capacity of this connection?

Answer 15

36-V output with 100-A-hr capacity.

Question 16

What is the voltage produced by a silicon solar cell?

Answer 16

Silicon solar cells produce an open-circuit voltage of 0.5 volts per cell in direct sunlight.

Question 17

What determines the current capacity of a solar cell?

Answer 17

The amount of current produced by a solar cell is determined by the surface area.

Question 18

A solar cell can produce a voltage of 0.5 V and has a current capacity of 0.1 A. How many cells should be connected in series and parallel to produce an output of 6V at 0.3A?

Answer 18

12 cells should be ran in series to produce the desired voltage and that would need to be repeated to create 3 groups of 12 cells to be ran in parallel in order to produce the desired ampere output. 36 solar cells in total would be required.

Question 19

What determines the amount of voltage produced by a thermocouple?

Answer 19

The amount of voltage produced by a thermocouple is determined by the type of materials used and the temperature difference between the ends of the junction.

Question 20

A thermocouple is to be used to measure a temperature of 2800F. Which type or types of thermocouples can be used to measure this temperature?

Answer 20

Types R, S, & B.

Question 21

What materials are used in the construction of a type J thermocouple?

Answer 21

Iron & Constantan

Question 22

What does the word piezo mean?

Answer 22

The word piezo, pronounced “pee-ay-zo,” is derived from the Greek word for pressure. Piezoelectricity is produced by some materials when they are placed under pressure.

Question 23

Three 12-V, 100-A-hr batteries are connected in parallel. What are the output voltage and A-hr capacity of this connection?

Answer 23

12-V output and 300-A-hr capacity.