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Advice For Physics

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On request of GorgeousEyes, here is more on the electricity chapter:

The effective resistance in series = The sum of all the Resistors in the circuit.
Lets say that R1, R2, R3 are three resistors in series. The effective resistance = R1 + R2 + R3.
The current is always the SAME throughout the circuit in SERIES. It is calculated by Current = Voltage/EFFECTIVE resistance. Remember, the current is always calculated using the effective resistance in series.
The voltage across each COMPONENT is different. The component could be a bulb, resistor, etc. The voltage is calculated by V = IR, where I is the constant current in the circuit and R is the resistance of the component.

The effective resistance in parallel is calculated by 1/Re = 1/R1 + 1/R2 + 1/R3. When you get 1/Re, the effective resistance is the reciprocal of the number you get, i.e. if you get 1/Re = 5, then the effective resistance = 1/5.
The voltage is always the SAME throughout the circuit in PARALLEL. It is always going to be the same through every component, the e.m.f (total voltage of battery) = the p.d. (voltage across component) across every component.
The current is different across every component in PARALLEL. It is calculated using Current = Voltage/RESISTANCE OF COMPONENT. Remember, in parallel, the current flowing though each component is calculated and the total current flowing is the sum of all these currents. Let's say that there are 3 resistors in a parallel circuit. The voltage will be same through out. The current across each component = V/R. The total current = I1 + I2 + I1. Where I1, I2, I3 are currents across EACH COMPONENT.

A potential divider is a series circuit. It works on the basis that the voltage across a component is different in series circuit. Now, we know that V=IR and that the current in series is the same throughout. So, a potential divider works by two DIFFERENT resistance components across a battery, the component with the higher resistance is the one with the HIGHER potential difference (voltage) across it (using V=IR). This means the since the current is same, the component with a higher resistance will have higher voltage across it and the one with lower resistance will have lower resistance across it.
 
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