Given that R1 = 10 Ω, R2 = 40Ω, R3 = 30Ω, R4 = 20Ω and RA is the parallel combination of R1 and R2 whereas RB is the parallel combination of R3 and R4. Combination RA is connected to the positive terminal of 12 V battery while combination RB is connected to the negative terminal. Ammeter A is connected between the resistors RA and RB.
(i) Find RA and RB Also calculate total resistance in the circuit.
(ii) Daw the circuit diagram showing above combinations connected to battery and ammeter.
(i) Resistors are in parallel when each resistor is connected directly to the voltage source by connecting wires having negligible resistance. Each resistor thus has the full voltage of the source applied to it.
Resistors are in series whenever the flow of charge, called the current, must flow through devices sequentially.
Since, Ra is connected to the positive terminal and Rb is connected to the negative terminal, Hence they are in series.
Therefore, total resistance,
(ii)
Major Features of Resistors in Series
1. Series resistances add: RA= R1+ R2+R3
2. The same current flows through each resistor in series.
3. Individual resistors in series do not get the total source voltage, but divide it.
Major Features of Resistors in Parallel
1. Parallel resistance is smaller than any individual resistance in the combination.
2. Each resistor in parallel has the same full voltage of the source applied to it. (Power distribution systems most often use parallel connections to supply the myriad devices served with the same voltage and to allow them to operate independently.)
3. Parallel resistors do not each get the total current; they divide it.