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Lump used in calibrating photo-tubes.
Standard Illuminant A. This temperature is on the 1931 I.C.I. (c2=14350) and would be 2842 on the present-day International Temperature Scale.
115-volt, 25-watt vacuum lamp.
115-volt, 250-watt drying lamp.
Special lamp.
Tables (4)
Table I
Spectral and total emissivities of tungsten.
Temperature
Wave-length
Total emissivity
0.30μ
0.38
0.467
0.665
0.8
1.0
1.5
1.8
2.0
2.5
3.0
4.0
1200°K
0.503
0.495
0.482
0.452
0.428
0.390
0.275
0.177
0.148
0.127
0.116
0.100
0.138
1500
.502
.492
.476
.445
.422
.385
.280
.191
.164
.145
.132
.115
.192
1800
.500
.488
.472
.439
.417
.382
.284
.206
.180
.161
.148
.127
.236
2000
.498
.485
.469
.435
.414
.380
.287
.215
.191
.170
.158
.135
.259
2200
.496
.482
.466
.431
.410
.378
.290
.225
.201
.180
.167
.144
.278
2500
.493
.477
.462
.425
.405
.375
.295
.240
.217
.195
.180
.155
.301
2600
.492
.476
.460
.423
.403
.373
.297
.245
.222
.200
.184
.159
.309
2700
.491
.475
.459
.421
.401
.372
.298
.249
.228
.205
.188
.163
.315
2800
.490
.473
.458
.419
.399
.371
.299
.254
.233
.210
.192
.167
.321
2900
.489
.472
.456
.417
.398
.370
.300
.259
.239
.215
.197
.170
.329
3000
.488
.470
.455
.415
.396
.368
.302
.264
.245
.220
.200
.173
.334
3200
.486
.468
.452
.411
.392
.366
.305
.273
.255
.231
.208
.180
.341
3400
.484
.465
.450
.407
.388
.363
.308
.283
.265
.241
.216
.186
.348
For λ=1.27μ the spectral emissivity is constant and equals 0.335.
Lump used in calibrating photo-tubes.
Standard Illuminant A. This temperature is on the 1931 I.C.I. (c2=14350) and would be 2842 on the present-day International Temperature Scale.
115-volt, 25-watt vacuum lamp.
115-volt, 250-watt drying lamp.
Special lamp.