Definition
There can be two combinations of resistors in a circuit as per appropriate needs. Why? Because often times, there is only one source of Potential Difference and multiple appliances require different current, voltage, etc. To counter that, resistors are used to manipulate such parameters.
Series Connection
In this circuit, the resistors are put one by one in the same wire, Thus, the resistance is added up.
- In this connection, the voltage changes, but current stays the same
Equivalent Resistance
Since, voltages are different,
Now, by Ohm’s Law,
Since, the current stays the same:
Parallel Connection
In this circuit, the resistors are put parallelly to each other. The reciprocal of the equivalent resistance is the sum of the reciprocals of the resistors.
- In this connection, voltage stays the same, but current is different
Equivalent Resistance
Since, currents are different,
By Ohm’s Law,
Since voltages are the same:
Voltmeter and Ammeter
Voltmeter is to measure the potential difference across two points. It has a high resistance, and thus placed parallelly in a circuit. Because the resistance is so high, the current that passes through it is minute compared to the current flowing across the two points. What happens if you put it in a series? It would display the potential flowing through it, which would be zero, since the resistance is so high.
Ammeter is to measure the current in the circuit. It has a low resistance, thus can be placed in series.
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Flashcards
What is the series connection and formula for equivalent resistance? ? In this circuit, the resistors are put one by one in the same wire,
- In this connection, the voltage changes, but current stays the same
What is the parallel connection and formula for equivalent resistance? ? In this circuit, the resistors are put parallelly to each other. The reciprocal of the equivalent resistance is the sum of the reciprocals of the resistors.
- In this connection, voltage stays the same, but current is different
In {{Series}} connection, the {{voltage changes, but current stays the same}}
In {{Parallel}} connection, the {{voltage stays the same, but current is different}}
What is a voltmeter and how is it placed in a circuit? ? Voltmeter is to measure the potential difference across two points. It has a high resistance, and thus placed parallelly in a circuit.
What is an ammeter and how is it placed in a circuit? ? Ammeter is to measure the current in the circuit. It has a low resistance, thus can be placed in series.