Home » Archimedes archive » Acorn User » AU 1997-01 B.adf » Regulars » StarInfo/Allen/!Ignotum/Formulae/Formulae/Elct
StarInfo/Allen/!Ignotum/Formulae/Formulae/Elct
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » Archimedes archive » Acorn User » AU 1997-01 B.adf » Regulars |
| Filename: | StarInfo/Allen/!Ignotum/Formulae/Formulae/Elct |
| Read OK: | ✔ |
| File size: | 0881 bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
# Physics > Electromagnetism # New entries should take the form of: # Formula # Note 1 # Note 2 # Note 3 # Note 4 # Note 5 # Formula # Note 1 # And so on... # To fit snugly into the window, each line should be no longer # than 42 characters. # There is a limit of 25 formulas per topic. # Any notes should be made here, at the beginning and should # be preceeded by a hash (#). F=BIl In a magnetic field: F=force B=field strength (known as flux density) I=current flowing l=length of wire in field F=BQv For a moving charge: F=force B=field strength/flux density Q=charge v=velocity perpendicular to field B=u0NI/l Inside a solenoid (or coil): B=field strength/flux density u0=permeability of free space=4PI�10^-7 N=number of turns I=current flowing, l=length B=u0I/2PIr Near a straight wire: B=field strength/flux density u0=permeability of free space=4PI�10^-7 I=current flowing r=radial distance from wire B=u0NI/2r In the centre of a circular coil: B=field strength/flux density u0=permeability of free space=4PI�10^-7 N=number turns, I=current flowing r=radius of coil reluctance=l/u0urA In a magnetic circuit, where: l=length u0=permeability of free space=4PI�10^-7 ur=relative permeability A=area flux=IN/reluctance Where: I=current N=number of turns E=N(df/dt) In induction, where: E=induced emf N=number of turns df/dt=rate of change of flux E=M(dI/dt) In induction, where: E=emf in secondary M=mutual inductance dI/dt=rate of change of current V=L(dI/dt) In induction, where: V=potential difference across coil L=self inductance dI/dt=rate of change of current Es=VpNs/Np In transformers, where: Es=emf in secondary Vp=potential difference across primary Ns and Np=number of turns in secondary or primary IpVp>IsEs In transformers, where: Ip and Is=currents in primary/secondary Vp=potential difference across primary Es=emf in secondary Irms=I0/2^� For alternating current, where: Irms=root mean square of the current I0=peak current 2PIf=w=1/(LC)^� For electrical oscillation, where: f=resonant frequency w=angular frequency L=inductance C=capacitance
00000000 23 20 50 68 79 73 69 63 73 20 3e 20 45 6c 65 63 |# Physics > Elec| 00000010 74 72 6f 6d 61 67 6e 65 74 69 73 6d 0a 0a 23 20 |tromagnetism..# | 00000020 4e 65 77 20 65 6e 74 72 69 65 73 20 73 68 6f 75 |New entries shou| 00000030 6c 64 20 74 61 6b 65 20 74 68 65 20 66 6f 72 6d |ld take the form| 00000040 20 6f 66 3a 0a 23 20 20 20 20 20 46 6f 72 6d 75 | of:.# Formu| 00000050 6c 61 0a 23 20 20 20 20 20 4e 6f 74 65 20 31 0a |la.# Note 1.| 00000060 23 20 20 20 20 20 4e 6f 74 65 20 32 0a 23 20 20 |# Note 2.# | 00000070 20 20 20 4e 6f 74 65 20 33 0a 23 20 20 20 20 20 | Note 3.# | 00000080 4e 6f 74 65 20 34 0a 23 20 20 20 20 20 4e 6f 74 |Note 4.# Not| 00000090 65 20 35 0a 23 20 20 20 20 20 46 6f 72 6d 75 6c |e 5.# Formul| 000000a0 61 0a 23 20 20 20 20 20 4e 6f 74 65 20 31 0a 23 |a.# Note 1.#| 000000b0 20 20 20 20 20 41 6e 64 20 73 6f 20 6f 6e 2e 2e | And so on..| 000000c0 2e 0a 23 20 54 6f 20 66 69 74 20 73 6e 75 67 6c |..# To fit snugl| 000000d0 79 20 69 6e 74 6f 20 74 68 65 20 77 69 6e 64 6f |y into the windo| 000000e0 77 2c 20 65 61 63 68 20 6c 69 6e 65 20 73 68 6f |w, each line sho| 000000f0 75 6c 64 20 62 65 20 6e 6f 20 6c 6f 6e 67 65 72 |uld be no longer| 00000100 0a 23 20 74 68 61 6e 20 34 32 20 63 68 61 72 61 |.# than 42 chara| 00000110 63 74 65 72 73 2e 0a 23 20 54 68 65 72 65 20 69 |cters..# There i| 00000120 73 20 61 20 6c 69 6d 69 74 20 6f 66 20 32 35 20 |s a limit of 25 | 00000130 66 6f 72 6d 75 6c 61 73 20 70 65 72 20 74 6f 70 |formulas per top| 00000140 69 63 2e 0a 0a 23 20 41 6e 79 20 6e 6f 74 65 73 |ic...# Any notes| 00000150 20 73 68 6f 75 6c 64 20 62 65 20 6d 61 64 65 20 | should be made | 00000160 68 65 72 65 2c 20 61 74 20 74 68 65 20 62 65 67 |here, at the beg| 00000170 69 6e 6e 69 6e 67 20 61 6e 64 20 73 68 6f 75 6c |inning and shoul| 00000180 64 0a 23 20 62 65 20 70 72 65 63 65 65 64 65 64 |d.# be preceeded| 00000190 20 62 79 20 61 20 68 61 73 68 20 28 23 29 2e 0a | by a hash (#)..| 000001a0 0a 46 3d 42 49 6c 0a 49 6e 20 61 20 6d 61 67 6e |.F=BIl.In a magn| 000001b0 65 74 69 63 20 66 69 65 6c 64 3a 0a 46 3d 66 6f |etic field:.F=fo| 000001c0 72 63 65 0a 42 3d 66 69 65 6c 64 20 73 74 72 65 |rce.B=field stre| 000001d0 6e 67 74 68 20 28 6b 6e 6f 77 6e 20 61 73 20 66 |ngth (known as f| 000001e0 6c 75 78 20 64 65 6e 73 69 74 79 29 0a 49 3d 63 |lux density).I=c| 000001f0 75 72 72 65 6e 74 20 66 6c 6f 77 69 6e 67 0a 6c |urrent flowing.l| 00000200 3d 6c 65 6e 67 74 68 20 6f 66 20 77 69 72 65 20 |=length of wire | 00000210 69 6e 20 66 69 65 6c 64 0a 46 3d 42 51 76 0a 46 |in field.F=BQv.F| 00000220 6f 72 20 61 20 6d 6f 76 69 6e 67 20 63 68 61 72 |or a moving char| 00000230 67 65 3a 0a 46 3d 66 6f 72 63 65 0a 42 3d 66 69 |ge:.F=force.B=fi| 00000240 65 6c 64 20 73 74 72 65 6e 67 74 68 2f 66 6c 75 |eld strength/flu| 00000250 78 20 64 65 6e 73 69 74 79 0a 51 3d 63 68 61 72 |x density.Q=char| 00000260 67 65 0a 76 3d 76 65 6c 6f 63 69 74 79 20 70 65 |ge.v=velocity pe| 00000270 72 70 65 6e 64 69 63 75 6c 61 72 20 74 6f 20 66 |rpendicular to f| 00000280 69 65 6c 64 0a 42 3d 75 30 4e 49 2f 6c 0a 49 6e |ield.B=u0NI/l.In| 00000290 73 69 64 65 20 61 20 73 6f 6c 65 6e 6f 69 64 20 |side a solenoid | 000002a0 28 6f 72 20 63 6f 69 6c 29 3a 0a 42 3d 66 69 65 |(or coil):.B=fie| 000002b0 6c 64 20 73 74 72 65 6e 67 74 68 2f 66 6c 75 78 |ld strength/flux| 000002c0 20 64 65 6e 73 69 74 79 0a 75 30 3d 70 65 72 6d | density.u0=perm| 000002d0 65 61 62 69 6c 69 74 79 20 6f 66 20 66 72 65 65 |eability of free| 000002e0 20 73 70 61 63 65 3d 34 50 49 d7 31 30 5e 2d 37 | space=4PI.10^-7| 000002f0 0a 4e 3d 6e 75 6d 62 65 72 20 6f 66 20 74 75 72 |.N=number of tur| 00000300 6e 73 0a 49 3d 63 75 72 72 65 6e 74 20 66 6c 6f |ns.I=current flo| 00000310 77 69 6e 67 2c 20 6c 3d 6c 65 6e 67 74 68 0a 42 |wing, l=length.B| 00000320 3d 75 30 49 2f 32 50 49 72 0a 4e 65 61 72 20 61 |=u0I/2PIr.Near a| 00000330 20 73 74 72 61 69 67 68 74 20 77 69 72 65 3a 0a | straight wire:.| 00000340 42 3d 66 69 65 6c 64 20 73 74 72 65 6e 67 74 68 |B=field strength| 00000350 2f 66 6c 75 78 20 64 65 6e 73 69 74 79 0a 75 30 |/flux density.u0| 00000360 3d 70 65 72 6d 65 61 62 69 6c 69 74 79 20 6f 66 |=permeability of| 00000370 20 66 72 65 65 20 73 70 61 63 65 3d 34 50 49 d7 | free space=4PI.| 00000380 31 30 5e 2d 37 0a 49 3d 63 75 72 72 65 6e 74 20 |10^-7.I=current | 00000390 66 6c 6f 77 69 6e 67 0a 72 3d 72 61 64 69 61 6c |flowing.r=radial| 000003a0 20 64 69 73 74 61 6e 63 65 20 66 72 6f 6d 20 77 | distance from w| 000003b0 69 72 65 0a 42 3d 75 30 4e 49 2f 32 72 0a 49 6e |ire.B=u0NI/2r.In| 000003c0 20 74 68 65 20 63 65 6e 74 72 65 20 6f 66 20 61 | the centre of a| 000003d0 20 63 69 72 63 75 6c 61 72 20 63 6f 69 6c 3a 0a | circular coil:.| 000003e0 42 3d 66 69 65 6c 64 20 73 74 72 65 6e 67 74 68 |B=field strength| 000003f0 2f 66 6c 75 78 20 64 65 6e 73 69 74 79 0a 75 30 |/flux density.u0| 00000400 3d 70 65 72 6d 65 61 62 69 6c 69 74 79 20 6f 66 |=permeability of| 00000410 20 66 72 65 65 20 73 70 61 63 65 3d 34 50 49 d7 | free space=4PI.| 00000420 31 30 5e 2d 37 0a 4e 3d 6e 75 6d 62 65 72 20 74 |10^-7.N=number t| 00000430 75 72 6e 73 2c 20 49 3d 63 75 72 72 65 6e 74 20 |urns, I=current | 00000440 66 6c 6f 77 69 6e 67 0a 72 3d 72 61 64 69 75 73 |flowing.r=radius| 00000450 20 6f 66 20 63 6f 69 6c 0a 72 65 6c 75 63 74 61 | of coil.relucta| 00000460 6e 63 65 3d 6c 2f 75 30 75 72 41 0a 49 6e 20 61 |nce=l/u0urA.In a| 00000470 20 6d 61 67 6e 65 74 69 63 20 63 69 72 63 75 69 | magnetic circui| 00000480 74 2c 20 77 68 65 72 65 3a 0a 6c 3d 6c 65 6e 67 |t, where:.l=leng| 00000490 74 68 0a 75 30 3d 70 65 72 6d 65 61 62 69 6c 69 |th.u0=permeabili| 000004a0 74 79 20 6f 66 20 66 72 65 65 20 73 70 61 63 65 |ty of free space| 000004b0 3d 34 50 49 d7 31 30 5e 2d 37 0a 75 72 3d 72 65 |=4PI.10^-7.ur=re| 000004c0 6c 61 74 69 76 65 20 70 65 72 6d 65 61 62 69 6c |lative permeabil| 000004d0 69 74 79 0a 41 3d 61 72 65 61 0a 66 6c 75 78 3d |ity.A=area.flux=| 000004e0 49 4e 2f 72 65 6c 75 63 74 61 6e 63 65 0a 57 68 |IN/reluctance.Wh| 000004f0 65 72 65 3a 0a 49 3d 63 75 72 72 65 6e 74 0a 4e |ere:.I=current.N| 00000500 3d 6e 75 6d 62 65 72 20 6f 66 20 74 75 72 6e 73 |=number of turns| 00000510 0a 0a 0a 45 3d 4e 28 64 66 2f 64 74 29 0a 49 6e |...E=N(df/dt).In| 00000520 20 69 6e 64 75 63 74 69 6f 6e 2c 20 77 68 65 72 | induction, wher| 00000530 65 3a 0a 45 3d 69 6e 64 75 63 65 64 20 65 6d 66 |e:.E=induced emf| 00000540 0a 4e 3d 6e 75 6d 62 65 72 20 6f 66 20 74 75 72 |.N=number of tur| 00000550 6e 73 0a 64 66 2f 64 74 3d 72 61 74 65 20 6f 66 |ns.df/dt=rate of| 00000560 20 63 68 61 6e 67 65 20 6f 66 20 66 6c 75 78 0a | change of flux.| 00000570 0a 45 3d 4d 28 64 49 2f 64 74 29 0a 49 6e 20 69 |.E=M(dI/dt).In i| 00000580 6e 64 75 63 74 69 6f 6e 2c 20 77 68 65 72 65 3a |nduction, where:| 00000590 0a 45 3d 65 6d 66 20 69 6e 20 73 65 63 6f 6e 64 |.E=emf in second| 000005a0 61 72 79 0a 4d 3d 6d 75 74 75 61 6c 20 69 6e 64 |ary.M=mutual ind| 000005b0 75 63 74 61 6e 63 65 0a 64 49 2f 64 74 3d 72 61 |uctance.dI/dt=ra| 000005c0 74 65 20 6f 66 20 63 68 61 6e 67 65 20 6f 66 20 |te of change of | 000005d0 63 75 72 72 65 6e 74 0a 0a 56 3d 4c 28 64 49 2f |current..V=L(dI/| 000005e0 64 74 29 0a 49 6e 20 69 6e 64 75 63 74 69 6f 6e |dt).In induction| 000005f0 2c 20 77 68 65 72 65 3a 0a 56 3d 70 6f 74 65 6e |, where:.V=poten| 00000600 74 69 61 6c 20 64 69 66 66 65 72 65 6e 63 65 20 |tial difference | 00000610 61 63 72 6f 73 73 20 63 6f 69 6c 0a 4c 3d 73 65 |across coil.L=se| 00000620 6c 66 20 69 6e 64 75 63 74 61 6e 63 65 0a 64 49 |lf inductance.dI| 00000630 2f 64 74 3d 72 61 74 65 20 6f 66 20 63 68 61 6e |/dt=rate of chan| 00000640 67 65 20 6f 66 20 63 75 72 72 65 6e 74 0a 0a 45 |ge of current..E| 00000650 73 3d 56 70 4e 73 2f 4e 70 0a 49 6e 20 74 72 61 |s=VpNs/Np.In tra| 00000660 6e 73 66 6f 72 6d 65 72 73 2c 20 77 68 65 72 65 |nsformers, where| 00000670 3a 0a 45 73 3d 65 6d 66 20 69 6e 20 73 65 63 6f |:.Es=emf in seco| 00000680 6e 64 61 72 79 0a 56 70 3d 70 6f 74 65 6e 74 69 |ndary.Vp=potenti| 00000690 61 6c 20 64 69 66 66 65 72 65 6e 63 65 20 61 63 |al difference ac| 000006a0 72 6f 73 73 20 70 72 69 6d 61 72 79 0a 4e 73 20 |ross primary.Ns | 000006b0 61 6e 64 20 4e 70 3d 6e 75 6d 62 65 72 20 6f 66 |and Np=number of| 000006c0 20 74 75 72 6e 73 20 69 6e 20 73 65 63 6f 6e 64 | turns in second| 000006d0 61 72 79 20 6f 72 0a 70 72 69 6d 61 72 79 0a 49 |ary or.primary.I| 000006e0 70 56 70 3e 49 73 45 73 0a 49 6e 20 74 72 61 6e |pVp>IsEs.In tran| 000006f0 73 66 6f 72 6d 65 72 73 2c 20 77 68 65 72 65 3a |sformers, where:| 00000700 0a 49 70 20 61 6e 64 20 49 73 3d 63 75 72 72 65 |.Ip and Is=curre| 00000710 6e 74 73 20 69 6e 20 70 72 69 6d 61 72 79 2f 73 |nts in primary/s| 00000720 65 63 6f 6e 64 61 72 79 0a 56 70 3d 70 6f 74 65 |econdary.Vp=pote| 00000730 6e 74 69 61 6c 20 64 69 66 66 65 72 65 6e 63 65 |ntial difference| 00000740 20 61 63 72 6f 73 73 20 70 72 69 6d 61 72 79 0a | across primary.| 00000750 45 73 3d 65 6d 66 20 69 6e 20 73 65 63 6f 6e 64 |Es=emf in second| 00000760 61 72 79 0a 0a 49 72 6d 73 3d 49 30 2f 32 5e bd |ary..Irms=I0/2^.| 00000770 0a 46 6f 72 20 61 6c 74 65 72 6e 61 74 69 6e 67 |.For alternating| 00000780 20 63 75 72 72 65 6e 74 2c 20 77 68 65 72 65 3a | current, where:| 00000790 0a 49 72 6d 73 3d 72 6f 6f 74 20 6d 65 61 6e 20 |.Irms=root mean | 000007a0 73 71 75 61 72 65 20 6f 66 20 74 68 65 20 63 75 |square of the cu| 000007b0 72 72 65 6e 74 0a 49 30 3d 70 65 61 6b 20 63 75 |rrent.I0=peak cu| 000007c0 72 72 65 6e 74 0a 0a 0a 32 50 49 66 3d 77 3d 31 |rrent...2PIf=w=1| 000007d0 2f 28 4c 43 29 5e bd 0a 46 6f 72 20 65 6c 65 63 |/(LC)^..For elec| 000007e0 74 72 69 63 61 6c 20 6f 73 63 69 6c 6c 61 74 69 |trical oscillati| 000007f0 6f 6e 2c 20 77 68 65 72 65 3a 0a 66 3d 72 65 73 |on, where:.f=res| 00000800 6f 6e 61 6e 74 20 66 72 65 71 75 65 6e 63 79 0a |onant frequency.| 00000810 77 3d 61 6e 67 75 6c 61 72 20 66 72 65 71 75 65 |w=angular freque| 00000820 6e 63 79 0a 4c 3d 69 6e 64 75 63 74 61 6e 63 65 |ncy.L=inductance| 00000830 0a 43 3d 63 61 70 61 63 69 74 61 6e 63 65 0a 0a |.C=capacitance..| 00000840 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a 0a |................| * 00000880 0a |.| 00000881
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