What is Filament lamp: Definition and 13 Discussions

An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxidation. Current is supplied to the filament by terminals or wires embedded in the glass. A bulb socket provides mechanical support and electrical connections.
Incandescent bulbs are manufactured in a wide range of sizes, light output, and voltage ratings, from 1.5 volts to about 300 volts. They require no external regulating equipment, have low manufacturing costs, and work equally well on either alternating current or direct current. As a result, the incandescent bulb became widely used in household and commercial lighting, for portable lighting such as table lamps, car headlamps, and flashlights, and for decorative and advertising lighting.
Incandescent bulbs are much less efficient than other types of electric lighting, converting less than 5% of the energy they use into visible light. The remaining energy is lost as heat. The luminous efficacy of a typical incandescent bulb for 120 V operation is 16 lumens per watt, compared with 60 lm/W for a compact fluorescent bulb or 150 lm/W for some white LED lamps.Some applications use the heat generated by the filament. Heat lamps are made for uses such as incubators, lava lamps, and the Easy-Bake Oven toy. Quartz tube halogen infrared heaters are used for industrial processes such as paint curing or for space heating.
Incandescent bulbs typically have short lifetimes compared with other types of lighting; around 1,000 hours for home light bulbs versus typically 10,000 hours for compact fluorescents and 20,000–30,000 hours for lighting LEDs. Incandescent bulbs can be replaced by fluorescent lamps, high-intensity discharge lamps, and light-emitting diode lamps (LED). Some areas have implemented phasing out the use of incandescent light bulbs to reduce energy consumption.

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  1. ephphatha16

    Resistance of a tungsten filament bulb at 20 C

    I was looking for any credible sources who could reveal the resistance of a normal tungsten filament bulb at room temp 20 C? I heard its cold resistance is about 9.5ohms. Is that the resistance at rtp? Thanks a lot in advance!
  2. P

    Adiabatic switching time of a filament lamp

    Hello all. Firstly I am sorry if this is in the wrong place but I was unsure exactly where it fits in as it involves physics, integrated equations, and computer programming. I am trying to write an emulator for a machine which is running 256 filament lamps in a 16*16 matrix. I want to simulate...
  3. R

    Filament lamp model (derivation)

    Homework Statement State and use simple assumptions to show that ' Power is proportional to V^5' is the expected relationship for a pure tungsten filament bulb. Homework Equations V=IR I=dq/dt Q=mcT The Attempt at a Solution I tried to use a simple model where the rate of heat loss is...
  4. M

    Question about changing resistance and power

    Homework Statement So this was the question: The 60W filament lamp is connected to a 6.0 V battery. The resistance of the lamp in this circuit is 70 Ohms. Explain why this value differs from the value given in (a)(iv) when the lamp is connected to the 230V supply. My answer was: V=IR, P=IV...
  5. D

    Wire supplying current to a filament lamp doesnt get hot?

    Hi everyone, So one of my students has asked me a question which I'm not sure how to answer. The question is: Why does the wire that supplies current to the filament lamp in a light bulb not heat up, even though the filament itself does? Please let me know your thoughts! Thank you :)
  6. E

    Resistance-current characteristic in the case of filament lamp (investigation)

    Changing voltage - independent variable current flowing - independent variable The investigation was aimed at measuring current at different potential differences, before the filament lamp started to shine and when it was shining so as to observe both ohmic and non-ohmic behaviour. Also after...
  7. A

    Why filament intensity profile of filament lamp deviates from blackboady curve?

    doing experiment today in which the intensity profile of a filament lamp (of surface temp around 2000K I think) is studied by passing it through a rotating grating apparatus and then reading the output from oscilloscope. My question is why the intensity profile intensity profile the...
  8. K

    Filament lamp I/V characteristics lab problem.

    i have to have my lab report ready in the next 1 hour and i am stuck. in my experiment we had a varied power supply , an ammeter and a voltmetter both with small error (and digital). i have taken about 15 measurements of potential difference and its respective current. the circuit had in one...
  9. K

    Filament lamp I/V characteristics lab problem.

    Homework Statement i have to have my lab report ready in the next 1 hour and i am stuck. in my experiment we had a varied power supply , an ammeter and a voltmetter both with small error (and digital). i have taken about 15 measurements of potential difference and its respective current. the...
  10. P

    I=kV^n filament lamp hnc assignment

    Homework Statement what does k and n relate to? i can work them out but don't know exactly what they are. Homework Equations I=kV^n The Attempt at a Solution i think the k and n have something to do with temperature and the tungsten metal in the lamp (coefficient of resistance?)...
  11. D

    Current/Voltage relationship for a filament lamp?

    Hi there, First post here guys! :biggrin: Recently i have been assigned my coursework on measuring the resistance of a filament lamp whereby an experiment was carried out by increasing the voltage through the filament lamp in intervals of 0.5 volts and measuring the current. I have since made...
  12. M

    Is a filament lamp an ohmic device?

    From wikipedia: A filament lamp obeys ohms law within certain limits of voltage and current so does that mean it is an ohmic device? Also from wikipedia: Sounds reasonable as well. Im inclined to believe the second quote since there are only a few values that the filament lamp will...
  13. S

    Vacuum Filament Lamp Temperature Analysis

    I am using a Vacum filament lamp, i wanted to know will the temperature of the surface of the bulb will be same as room temp at 0V. the bulb is attached to a power supply. thanks