Voltage Divider - Understanding Two Circuits

[autopsygreen]

Very silly doubt...If say I had a voltage divider circuit with 2 equal Resistance say R applied between
1.V=5v and ground
2.V=5V and V=-5V
Whats the answers and what the difference?
I guess the answer for the 1 Q will be (5/2)...
Please explain the second ...Thank you

 

[Jiggy-Ninja]

(5v - -5v)/2

0v

 

[autopsygreen]

What confuses me is then why is the negative terminal said to be connected to ground.
Shouldnt that mean the ground and -5v are at same potential

 

[davenn]

What confuses me is then why is the negative terminal said to be connected to ground.
Shouldnt that mean the ground and -5v are at same potential

depends on if its a single rail supply...

+5V and GND (0V or negative line of power supply)

or a split supply where you have say...

+5V, 0V, -5V where the 0V rail may be connectd to GND via the PSU case and mains earth


take a 12V battery, you have a + and - terminal --- from a circuit point of view the - terminal can be called 0V

now take a mains sourced 12V power supply, you have a +12V rail and a -(neg) 0V rail.
that negative rail may be floating ie. not connected to the case of the equip. Or it may be connected to the case and that case is also connected to GND via the Earth lead of the mains cable.

just a few random thoughts ;)

Dave

 

[sophiecentaur]

By stipulating a +5 and -5V supply, you are implying that there is a 'zero volts' somewhere in the power supplies, connected to ground which defines their voltages wrt ground.