Knowledge (XXG)

Instrument error

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If the instrument has a needle which points to a scale graduated in steps of 0.1 units, then depending on the design of the instrument it is usually possible to estimate tenths between the successive marks on the scale, so it should be possible to read off the result to an accuracy of about 0.01
170:, or perhaps because a defect has arisen in the instrument since it was calibrated. Instruments should be calibrated against a standard instrument that is known to be accurate, and ideally the calibration should be repeated at intervals. The most rigorous standards are those maintained by a 166:. For example the instrument may always indicate a value 5% higher than the actual value; or perhaps the relationship between the indicated and actual values may be more complicated than that. A systematic error may arise because the instrument has been incorrectly 189:
If the users know the amount of the systematic error, they may decide to adjust for it manually rather than having the instrument expensively adjusted to eliminate the error: e.g. in the above example they might manually reduce all the values read by about 4.8%.
137:, or the difference between the actual value and the value indicated by the instrument. There can be errors of various types, and the overall error is the sum of the individual errors. 183: 239:
has its own built-in resistance, so if it is connected in series to an electrical circuit, it will slightly reduce the current flowing through the circuit.
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Sometimes the effect of random error can be reduced by repeating the measurement a few times and taking the average result.
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The act of taking the measurement may alter the quantity being measured. For example, an
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The range in amount of possible random errors is sometimes referred to as the
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The size of the systematic error is sometimes referred to as the
175: 15: 275: 209:how accurately the display can actually be read. 206:errors in the amount shown on the display, and 295: 8: 50:. Unsourced material may be challenged and 302: 288: 114:Learn how and when to remove this message 222:How accurately the display can be read 7: 252: 250: 48:adding citations to reliable sources 274:. You can help Knowledge (XXG) by 14: 254: 20: 331:Standards and measurement stubs 1: 214:Amount shown on the display 347: 249: 140:Types of errors include 270:-related article is a 172:standards organization 321:Measuring instruments 135:measuring instrument 44:improve this article 63:"Instrument error" 283: 282: 158:Systematic errors 144:systematic errors 124: 123: 116: 98: 338: 304: 297: 290: 258: 251: 127:Instrument error 119: 112: 108: 105: 99: 97: 56: 24: 16: 346: 345: 341: 340: 339: 337: 336: 335: 311: 310: 309: 308: 247: 245: 233: 224: 216: 196: 160: 120: 109: 103: 100: 57: 55: 41: 25: 12: 11: 5: 344: 342: 334: 333: 328: 323: 313: 312: 307: 306: 299: 292: 284: 281: 280: 259: 244: 241: 232: 229: 223: 220: 215: 212: 211: 210: 207: 195: 192: 159: 156: 155: 154: 151: 150:absolute error 148: 145: 129:refers to the 122: 121: 28: 26: 19: 13: 10: 9: 6: 4: 3: 2: 343: 332: 329: 327: 324: 322: 319: 318: 316: 305: 300: 298: 293: 291: 286: 285: 279: 277: 273: 269: 265: 260: 257: 253: 248: 242: 240: 238: 230: 228: 221: 219: 213: 208: 205: 204: 203: 201: 194:Random errors 193: 191: 187: 185: 181: 180:United States 177: 173: 169: 165: 157: 152: 149: 147:random errors 146: 143: 142: 141: 138: 136: 132: 128: 118: 115: 107: 104:December 2009 96: 93: 89: 86: 82: 79: 75: 72: 68: 65: –  64: 60: 59:Find sources: 53: 49: 45: 39: 38: 34: 29:This article 27: 23: 18: 17: 276:expanding it 261: 246: 234: 231:Other errors 225: 217: 197: 188: 161: 139: 126: 125: 110: 101: 91: 84: 77: 70: 58: 42:Please help 30: 268:measurement 186:in Europe. 153:other error 315:Categories 243:References 168:calibrated 74:newspapers 326:Metrology 264:standards 200:precision 182:, or the 31:does not 174:such as 164:accuracy 237:ammeter 227:units. 178:in the 88:scholar 52:removed 37:sources 90:  83:  76:  69:  61:  266:- or 262:This 133:of a 131:error 95:JSTOR 81:books 272:stub 176:NIST 67:news 35:any 33:cite 184:ISO 46:by 317:: 303:e 296:t 289:v 278:. 117:) 111:( 106:) 102:( 92:· 85:· 78:· 71:· 54:. 40:.

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