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# Earthing watch

1. http://i-want-to-study-engineering.org/q/earthed_loops/
does the earthing symbol mean that soon the current in the left hand circuit part becomes zero?
2. (Original post by runny4)
http://i-want-to-study-engineering.org/q/earthed_loops/
does the earthing symbol mean that soon the current in the left hand circuit part becomes zero?
No. It means that the part of the circuit to which it is connected is at 0 V.
3. (Original post by runny4)
http://i-want-to-study-engineering.org/q/earthed_loops/
does the earthing symbol mean that soon the current in the left hand circuit part becomes zero?
The earth can be considered an infinite source or sink of electrons. Taking away or adding to that sink will have no impact on the net charge of the earth, which remains constant.

The earth can therefore be considered an 'ideal' reference of 0V. i.e. The 'earth' potential cannot change no matter how much current/charge is sourced or sunk to/from it.
4. (Original post by uberteknik)
The earth can be considered an infinite source or sink of electrons. Taking away or adding to that sink will have no impact on the net charge of the earth, which remains constant.

The earth can therefore be considered an 'ideal' reference of 0V. i.e. The 'earth' potential cannot change no matter how much current/charge is sourced or sunk to/from it.
so it is just a point in the circuit at 0V as a reference and not a low resistance path like the earth wire in a fuse?
5. (Original post by atsruser)
No. It means that the part of the circuit to which it is connected is at 0 V.
so it is just a point in the circuit at 0V as a reference and not a low resistance path like the earth wire in a fuse?
6. (Original post by runny4)
so it is just a point in the circuit at 0V as a reference and not a low resistance path like the earth wire in a fuse?
Yes. The symbol is just an indication that voltages relative to that point are measured relative to 0 V.
7. (Original post by atsruser)
Yes. The symbol is just an indication that voltages relative to that point are measured relative to 0 V.
thanks and just to clarify the earth wire in a fuse is completely different?
8. (Original post by runny4)
thanks and just to clarify the earth wire in a fuse is completely different?
I'm not sure want you mean by "earth wire in a fuse". A fuse is simply a "weak" wire that is inserted in a circuit, so that if too much current flows, it overheats and melts, preventing any more current from flowing through the circuit.

A fuse doesn't connect a circuit to a 0 V point though. Both sides of a fuse are at the same voltage, more or less, since you want it to have pretty low resistance - it shouldn't interfere with the correct operation of the circuit. (It can't have precisely 0 resistance though, else it could never heat up).
9. (Original post by atsruser)
I'm not sure want you mean by "earth wire in a fuse". A fuse is simply a "weak" wire that is inserted in a circuit, so that if too much current flows, it overheats and melts, preventing any more current from flowing through the circuit.

A fuse doesn't connect a circuit to a 0 V point though. Both sides of a fuse are at the same voltage, more or less, since you want it to have pretty low resistance - it shouldn't interfere with the correct operation of the circuit. (It can't have precisely 0 resistance though, else it could never heat up).
http://www.bbc.co.uk/schools/gcsebit...lectrev2.shtml

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