Easy as Pie!
Electricity and Magnetism
Level
pending
In the shown circuit find the total resistance if the ammeter's reading is 5 A...neglect the internal resistance
N.B: the current direction is as shown in the circuit
The answer is 3.333.
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1 solution
since the potential difference remains unchanged between 2 points withe zero resistance among them ∴ as we go upwards with the current direction the voltage is 20 V and as we go downwards it remains 0 V till the ammeter's position since the reading is 5 A flowing through 1 ohm ∴ pot.diff is 5 V and as we go upwards it remains 5 V now we can calculate pot.diff across 5 ohms resistors which is 20-5= 15 V ∴ the current flowing through this resistor is 3 A now the remainder current is 2 A which flows through 1 ohm resistor (the one beside the 2 ohms resistor) ∴ pot.diff across the 1 ohm is 2 V and the pot.diff across 2 points of this resistor is 5+2= 7 V so the current which should flow through 7 ohms is 1 A to make the pot.diff = 7 V now we have total current which equals 6 A ∴ Rt=20/6 =3.333 app.