Inventing for Boys

by A. Frederick Collins

APPENDIX O

SOME ELECTRICAL SYMBOLS, TERMS AND FORMULAS

Symbols		Terms
E or EMF	=	Electromotive Force
I	=	Intensity of Current
R	=	Resistance
C	=	Capacity
Q	=	Quantity of Current
	=	Magneto-Motive Force
	=	Reluctance (magnetic resistance)
µ	=	Magnetic Permeability
W	=	Electric Energy
P	=	Electric Power

SOME DEFINITIONS

E or EMF, or electromotive force, is the force that moves a current through a conductor.

I, or intensity of current, or current as it is called for short, is the flow of electricity through a conductor.

R, or resistance is that property of a conductor which opposes the flow of the current.

SOME ELECTRICAL UNITS

Practical Units.		Electrical Quantity
	Volt	is the practical unit of EMF
	Ampere	is the practical unit of I
	Ohm	is the practical unit of R
	Watt	is the practical unit of P

OHM’S LAW

Since the intensity of an electric current varies directly as the electromotive force and inversely as the resistance, if you know the value of any two of the above units you can easily find the third.

Amperes	=	Volts	, or	I	=	E
		Ohms				R

Electromotive Force	=	Current	, or	E	=	I
		Resistance				R

Resistance	=	Electromotive Force	, or	R	=	E
		Current				I

To Find Power of an Electric Current in Terms of Horse Power

One Watt	=	1 volt × 1 ampere
746 Watts	=	1 horse power.

To find the power of an electric current in terms of horse-power, find the number of watts by multiplying the volts by the amperes and divide the watts by 746 and the result will give you the horse-power of the current.

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APPENDIX P
NUMBER, DIAMETER, CAPACITY, WEIGHT, AND RESISTANCE OF PURE COPPER WIRE

Gage, B. & S. No.	Diameter in 1000ths.	Sectional Area in Circular Mils.	Capacity in Amperes	OHMS			FEET		POUNDS
				Per 1,000 feet	Per Mile	Per Pound	Per Pound	Per Ohm	Per 1,000 feet	Per Ohm
0000	.460	211600.	312.	.0490	.2590	.00007	1.5612	20497.7	640.59	12987.
000	.40964	167805.	262.	.0618	.3266	.00012	1.9687	16255.27	507.85	8333.
00	.3648	133079.	220.	.0780	.4118	.00019	2.4824	12891.37	402.83	5263.
0	.32486	105534.	185.	.0983	.5190	.00031	3.1303	10223.08	319.45	3225.
1	.2893	83694.	156.	.1240	.6549	.00049	3.9471	8107.49	253.34	2041.
2	.25763	66373.	131.	.1564	.8258	.00078	4.9772	6429.58	200.91	1228.
3	.22942	52634.	110.	.1972	1.0414	.00125	6.2765	5098.61	159.32	800.
4	.20431	41473.	92.3	.2486	1.313	.00198	7.9141	4043.6	126.35	505.
5	.18194	33102.	77.6	.3136	1.655	.00314	9.9798	3206.61	100.20	318.
6	.16202	26251.	65.2	.3954	2.088	.00499	12.5847	2542.89	79.462	200.
7	.14428	20817.	54.8	.4987	2.633	.00792	15.8696	2015.51	63.013	126.
8	.12849	16510.	46.1	.6529	3.3	.0125	20.0097	1599.3	49.976	80.
9	.11443	13094.	38.7	.7892	4.1	.0197	25.229	1268.44	39.636	50.
10	.10189	10382.	32.5	.8441	4.4	.0270	31.8212	1055.66	31.426	37.
11	.09074	8234.	27.3	1.254	6.4	.0501	40.1202	797.649	24.924	20.
12	.08080	6530.	23.	1.580	8.3	.079	50.5906	632.555	19.766	12.65
13	.07196	5178.	19.3	1.995	10.4	.127	63.7948	501.63	15.674	7.87
14	.06408	4107.	16.2	2.504	13.2	.200	80.4415	397.822	12.435	5.00
15	.05706	3257.	13.6	3.172	16.7	.320	101.4365	315.482	9.859	3.12
16	.05082	2583.	11.5	4.001	23.	.512	127.12	250.184	7.819	1.95
17	.04525	2048.	9.6	5.04	26.	.811	161.29	198.409	6.199	1.23
18	.04030	1624.	8.1	6.36	33.	1.29	203.374	157.35	4.916	.775
19	.03589	1288.		8.25	43.	2.11	256.468	124.777	3.899	.473
20	.03196	1021.		10.12	53.	3.27	323.399	98.9533	3.094	.305
21	.02846	810.		12.76	68.	5.20	407.815	78.473	2.452	.192
22	.02534	642.		16.25	85.	8.35	514.193	62.236	1.945	.119
23	.02257	509.		20.30	108.	13.3	648.452	49.3504	1.542	.075
24	.0201	404.		25.60	135.	20.9	817.688	39.1365	1.223	.047
25	.0179	320.		32.2	170.	32.2	1031.038	31.0381	.9699	.030
26	.01594	254.		40.7	214.	52.9	1300.180	24.6131	.7692	.0187
27	.01419	201.		51.3	270.	84.2	1639.49	19.5191	.6099	.0118
28	.01264	159.8		64.8	343.	134.	2067.364	15.4793	.4807	.0074
29	.01125	126.7		81.6	432.	213.	2606.959	12.2854	.3835	.0047
30	.01002	100.5		103.	538.	338.	3287.084	9.7355	.3002	.0029
31	.00892	79.7		130.	685.	539.	4414.49	7.7214	.2413	.0018
32	.00795	63.		164.	865.	856.	5226.915	6.1224	.1913	.0011
33	.00708	50.1		206.	1033.	1357.	6590.41	4.8557	.1517	.00076
34	.00630	39.74		260.	1389.	2166.	8312.8	3.8496	.1204	.00046
35	.00561	31.5		328.	1820.	3521.	10481.77	3.0530	.0956	.00028
36	.005	25.		414.	2200.	5469.	13214.16	2.4217	.0757	.00018
37	.00445	19.8		523.	2765.	8742.	16659.97	1.9208	.0600	.00011
38	.00396	15.72		660.	3486.	13722.	21013.25	1.5229	.0475	.00007
39	.00353	12.47		832.	4395.	21896.	26496.237	1.2077	.0375	.00004
40	.00314	9.88		1049.	5542.	34823.	33420.63	0.9798	.0299	.00002

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APPENDIX Q
NUMBER OF TURNS OF WIRE THAT CAN BE WOUND IN A GIVEN SPACE

No. B. & S. or American Gage	COTTON				SILK
	SINGLE		DOUBLE		SINGLE		DOUBLE
	Per Square Inch.	Per Square Qu. Inch	Per Square Inch.	Per Square Qu. Inch	Per Square Inch.	Per Square Qu. Inch	Per Square Inch.	Per Square Qu. Inch
20	676	42	576	36	841	52	676	42
21	842	53	625	39	961	60	842	53
22	1.024	64	729	45	1.225	76	1.024	64
23	1.024	81	900	56	1.521	95	1.296	81
24	1.600	100	1.089	68	1.936	121	1.600	100
25	1.849	115	1.296	81	2.304	144	1.849	115
26	2.209	138	1.440	90	2.916	182	2.209	138
27	2.500	156	1.600	100	3.249	206	2.500	156
28	3.025	189	1.849	115	4.096	254	3.025	189
29	3.481	218	2.025	126	4.761	297	3.481	218
30	4.356	272	2.500	156	6.400	400	4.356	272
31	5.001	315	2.704	169	7.769	485	5.041	315
32	5.929	370	3.025	189	9.025	564	5.929	370
33	7.089	443	3.481	218	11.025	689	7.089	443
34	7.769	485	3.600	225	12.321	770	7.769	485
35	8.100	506	3.844	240	13.689	855	8.100	506
36	10.000	625	4.356	272	17.689	1.105	10.000	625
37	11.025	689	4.761	297	20.164	1.240	11.025	689
38	12.321	770	5.041	315	23.716	1.482	12.321	770
39	13.689	855	5.476	342	27.556	1.722	13.689	855
40	15.625	976	5.929	370	32.761	2.047	15.625	976

(W. J. Clarke.)

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APPENDIX R
PRICES OF SINGLE AND DOUBLE SILK AND COTTON COVERED MAGNET WIRE

PRICE PER POUND

Size by B. & S. Gage	Single Covered.		Double Covered.
	Cotton	Silk	Cotton	Silk
16		$0.80		$1.02
17		.82		1.04
18		.84		1.06
19		.86		1.08
20	$0.58	.88	$0.64	1.12
21	.60	.90	.70	1.15
22	.62	.92	.74	1.22
23	.65	.96	.78	1.28
24	.68	1.02	.84	1.38
25	.73	1.10	.92	1.48
26	.80	1.20	1.00	1.65
27	.86	1.30	1.10	1.85
28	.92	1.40	1.20	2.00
29	.98	1.53	1.30	2.22
30	1.08	1.70	1.42	2.56
31	1.19	1.92	1.54	3.08
32	1.27	2.16	1.64	3.40
33	1.44	2.46	1.88	4.00
34	1.73	2.90	2.20	4.60
35	1.86	3.38	2.67	5.28
36	2.12	3.93	3.00	5.98
37	2.70	4.66	4.30	7.37
38	3.60	5.58	5.70	8.43
39	4.70	6.76	7.20	9.75
40	6.00	8.14	9.00	11.53

There is a discount of about 50 per cent. on the above prices though this is subject to change.

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APPENDIX S
A LIST OF SOME CHEMICAL ELEMENTS AND THEIR SYMBOLS

Element	Symbol
Aluminum	Al
Antimony	Sb
Argon	A
Arsenic	As
Barium	Bi
Boron	B
Bromine	Br
Cadmium	Cd
Calcium	Ca
Carbon	C
Chlorine	Cl
Chromium	Cr
Cobalt	Co
Copper	Cu
Fluorine	F
Gold	Au
Helium	He
Hydrogen	H
Iodine	I
Iron	Fe
Lead	Pb
Lithium	Li
Magnesium	Mg
Manganese	Mn
Mercury	Hg
Nickel	Ni
Nitrogen	N
Oxygen	O
Phosphorus	P
Potassium	K
Platinum	Pt
Silicon	Si
Silver	Ag
Sodium	Na
Strontium	Sr
Sulphur	S
Tin	Sn
Zinc	Zn

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APPENDIX T
THE COMMON NAMES OF SOME CHEMICALS

Common Name	Chemical Name
Alum	Sulphate of ammonium, or potassium, etc.
Aqua fortis	Nitric acid
Aqua regia	Concentrated nitric and hydrochloric acid mixed.
Baking soda	Sodium carbonate
Calomel	Mercurious chloride
Carbolic acid	Phenol
Caustic potash	Potassium hydroxide
Caustic soda	Sodium hydroxide
Chalk	Calcium carbonate
Copperas	Ferrous sulphate
Corrosive sublimate	Mercuric chloride
Cream of tartar	Potassium bitartrate
Epsom salts	Magnesium sulphate
Fire damp	Methane
Fool’s gold	Iron pyrites
Glauber’s salt	Sodium sulphate
Grape sugar	Glucose; a carbohydrate
Hartshorn	Aqueous solution of ammonia
Jeweler’s putty	Tin oxide
Laughing gas	Nitrous oxide
Lime	Calcium oxide
Lunar caustic	Silver nitrate
Mosaic gold	Tin bisulphide
Muriatic acid	Hydrochloric acid
Monsel’s salts	Basic ferric sulphate
Plaster of Paris	Calcium sulphate
Realgar	Red arsenic sulphide
Red lead	Lead oxide
Rochelle salt	Sodium potassium tartrate
Royal water	See Aqua regia
Sal ammoniac	Ammonium chloride
Salt (common)	Sodium chloride
Sal soda	Sodium carbonate
Salt of tartar	Potassium carbonate
Saltpeter	Potassium nitrate
Salts of lemon	Oxalic acid
Slacked lime	Calcium hydrate
Soda	Sodium carbonate
Spirits of salt	Hydrochloric acid
Sugar of lead	Lead acetate
Sugar of milk	Lactose
Tartar emetic	Potassium antimonious tartrate
Verdigris	Copper acetate
Vermilion	Mercuric sulphide
Vinegar	Dilute acetic acid
Vitriol, blue	Copper sulphate
Vitriol, green	Ferrous sulphate
Vitriol, oil of	Sulphuric acid
Vitriol, white	Zinc sulphate
Volatile alkali	Ammonia
Washing soda	Sodium carbonate
White lead	Lead carbonate
Zinc white	Zinc sulfid

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APPENDIX U
THE FOUR CHIEF THERMOMETRIC SCALES

Fig. 130. The four chief thermometric scales: réaumur, absolute, fahrenheit and centigrade

There are four different thermometer scales used for measuring temperature and these are (1) the Fahrenheit scale which is widely used for all ordinary purposes; (2) the Centigrade which is the standard scale used for scientific work since it is based on the decimal system; (3) the Réaumur scale which is largely used in Germany, and (4) the absolute scale which is reckoned from absolute zero, that is the point at which there is absolutely no heat. It is about 461 degrees Fahr., 274 degrees centigrade, and 219 degrees Réaumur below the zero of these scales.

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