# Understanding Voltages in a circuit

Discussion in 'General Electronics Chat' started by Abhinavrajan, Sep 5, 2016.

1. ### Abhinavrajan Thread Starter Member

Aug 7, 2016
73
1
Please look at the simple circuit and help me understand the concept of voltage.

1. Assume the circuit is in open condition. What would the voltage between point B and ground ? - Please answer this and help me understand a bit more clearly.

2. Assume the circuit is closed and current flows through it.

2a. What would be the value of voltage between point A and ground ?
2b. What would be the value of voltage between point B and ground ?

Please explain with some reason and in simple english. An example or analogy for the answers would be really great. Thanks.

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2. ### R!f@@ AAC Fanatic!

Apr 2, 2009
8,502
713
With Switch closed.
A is across the battery so A to GND has Battery Voltage.
B is same as ground. So No voltage

And Switch open.
A and B has same voltage respective to GND as battery since no current is flowing through circuit.

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3. ### AlbertHall Well-Known Member

Jun 4, 2014
1,371
258
1. With the switch open the voltage at both A & B will be 10V. A is simply the battery voltage. There is no current flowing so the voltage across the resistor is zero (V = I * R) and therefore the voltage at B is the same as A, 10V.
2a. The voltage at A is unchanged. It is the voltage across the battery.
2b. With the switch closed, B is connected directly to ground so there is zero voltage between B and ground. The difference between A & B is now equal to the battery voltage.
A the voltage at A
B the voltage at B
V voltage across the resistor
I current through the resistor
R the value of the resistor
V = I * R
I = V / R
I = (A - B) / R
I = (10V - 0V) / 10Ω
I = 10V / 10Ω
I = 1 amp.

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Aug 7, 2016
73
1
Thank you!

Aug 7, 2016
73
1
Thank you!