What is Emf: Definition and 938 Discussions

EMF measurements are measurements of ambient (surrounding) electromagnetic fields that are performed using particular sensors or probes, such as EMF meters. These probes can be generally considered as antennas although with different characteristics. In fact, probes should not perturb the electromagnetic field and must prevent coupling and reflection as much as possible in order to obtain precise results. There are two main types of EMF measurements:

broadband measurements: performed using a broadband probe, that is a device which senses any signal across a wide range of frequencies and is usually made with three independent diode detectors;
frequency selective measurements: in which the measurement system consists of a field antenna and a frequency selective receiver or spectrum analyzer allowing to monitor the frequency range of interest.EMF probes may respond to fields only on one axis, or may be tri-axial, showing components of the field in three directions at once. Amplified, active, probes can improve measurement precision and sensitivity but their active components may limit their speed of response.

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  1. B

    Two battery current & EMF problem

    The question was to find I1 I2 and E. I got those parts of the question correct. I1= 1 A I2 = 2A E = 15V. But the only reason I got these right is because the arrows for I1 & I2 were given in the attached figure. The directions of the current don't make sense to me. If the EMF from...
  2. M

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  3. I

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    Homework Statement Review problem. A flexible metallic wire with linear density 3.00 multiplied by 10-3 kg/m is stretched between two fixed clamps 64.0 cm apart and held under tension 301 N. A magnet is placed near the wire as shown in Figure P31.25. Assume that the magnet produces a uniform...
  4. I

    Calculating Induced EMF in a Coil

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  5. K

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  6. N

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  7. G

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  8. T

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  9. I

    How do I solve for current and emf in this circuit?

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  10. C

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  11. G

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  12. S

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  13. J

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  14. R

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  15. S

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  16. S

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  17. A

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  18. L

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  19. O

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  20. J

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  21. R

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  22. B

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  23. C

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  24. G

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  25. M

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  26. K

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  27. V

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  28. X

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  29. D

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  30. M

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  31. M

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  32. S

    Why is there no induced emf in electric motor?

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  33. P

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  34. R

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    Homework Statement http://img164.imageshack.us/img164/3313/qqqqo3.jpg Find the total magnetic flux through the coil at t=0 Given that the rate of change of flux at any time,t, is equal to 2 \pi f \phi sin 2 \pi ft, find the maximum instanteous value of the induced emf at any time & the...
  35. N

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  36. S

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  37. L

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    Homework Statement A torch battery has an emf of 6.0V and an internal resistance of 1 Ohms. What is the voltage measured by a voltmeter connected across the terminals of the battery, when the battery is connected to a bulb that draws 0.5 A from the battery? Anyways thanks I solved it.
  38. T

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  39. D

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  40. S

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  41. Redbelly98

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  42. A

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  43. N

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  44. E

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  45. S

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  46. B

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  47. S

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  48. G

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  49. G

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  50. G

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    A circular loop of wire has a changing magnetic field running through it...however, the magnetic field is not touching the wire; its contained so that it simply runs through the loop without touching the wire. Apparently, there is still an emf through the wire even though the magnetic field is...
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