A series circuit has two 5.0 on resistors and a power source of 9.0 volts. How will the current be affected and what will be another resistor (with a resistance of 7.5 ohms) is added to the circuit?

Question

Physics

Brooklyn Buck

11 December, 08:21

A series circuit has two 5.0 on resistors and a power source of 9.0 volts. How will the current be affected and what will be another resistor (with a resistance of 7.5 ohms) is added to the circuit?

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Answers (1)

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Evelin Stevens · Answer 1

The total resistance in a series circuit is just the sum of all the individual resistors in the circuit.

Before the new resistor is added, the total resistance in the circuit is

(5 ohms) + (5 ohms) = 10 ohms.

The current in any circuit is

(voltage of the power source) divided by (total resistance).

Right now, that's (9 volts) / (10 ohms) = 0.9 Amperes.

When the new resistor is added to the series circuit,

the new total resistance is

(5 ohms) + (5 ohms) + (7.5 ohms) = 17.5 ohms.

The new current is

(9 volts) / (17.5 ohms) = 0.514 Ampere (rounded)

The addition of the extra resistor caused the current to decrease

by (0.9 - 0.514) = 0.386 Ampere.

That's a decrease of 42.9% of the original current.