CBSE - X - Physics - Electricity
Q.1 In series connection, why does current remain same across the resistors but potential difference different? In parallel connection, why does potential difference remain same across the resistors but current different?
Q.2 In series combination of resistors, why does resistance increase and current flowing through the circuit decrease? In parallel combination, why does resistance decrease and current flowing the circuit increase?
- Series connection is a combnation of resistors connected end to end.
- It forms a linear connection arrangement of all the resistors connected in series.
- So the amount of current flowing through each resistor is equal to the amount of current flowing through the entire circuit.
- Thus, in series connection the current remains same across the resistors.
- The equivalent resistance of such resistors is given by the sum of resistances of all the resistors connected in series.
- This explains that the resistance of the entire circuit of resistors connected in series will be more than the resistance of the individual resistors.
- Resistance is the actual resistance to the flow of current through the circuit.
- Therefore as the equivalent resistance of the resistors connected in series gets added up, the flow of current in a series circuit decreases due to this added resistance.
- The resistors connected in parallel are connected such that their positive terminals and negative terminals respectively are connected together.
- The potential diffference is maintained across the the terminals of the resistors.
- This is the reason why the potential difference remains same across resistors connected in parallel.
- Equivalent resistance of the resistors connected in parallel is given by
- Thus the reciprocal of the equivalent resistance of resistors connected in parallel is the sum of the reciprocals of the resistances of the resistors in this combination.
- This numerically reduces the value of equivalent resistance with respect to the individual resistances.
- Hence the current in the parallel combination increases due to the decrease in the equivalent resistance of the parallel circuit.
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