Three resistors, of resistance R1, R2 and R3 respectively, are connected in parallel across acell. The cell has negligible internal resistance and electromotive force
Use the principle of conservation of charge to show that the total resistance R^t of thethree resistors can be found using the expression
1/Rt = 1/R1 + 1/R2 + 1/R3
Stuck on this physics as level question - resistivity watch
- Thread Starter
- 27-06-2016 19:37
- 27-06-2016 22:17
Conservation of charge, Q, gives that
Qt = Q1 + Q2 + Q2
It = I1 + I2 + I3
where I is the current, I = Q / t.
As the resistors are connected in parallel, they all have the same voltage V. So using Ohm's law, V = IR, gives
V/Rt = V/R1 + V/R2 + V/R3.
Divide by V to get the result.