Question

question 9
add an extra bulb in parallel to the circuit. what happens to the brightness of the other bulbs when you added this extra bulb?
o all of the bulbs get a little brighter
o all of the bulbs stayed the same brightness
o all of the bulbs get a little dimmer

Explanation:

To solve this, we analyze the circuit configuration (assuming parallel or series, but the key is adding a bulb in parallel).

Step 1: Recall Parallel Circuit Properties

In a parallel circuit, voltage across each branch is equal to the source voltage. Resistance of each bulb (\(R\)) is constant. Power \(P = \frac{V^2}{R}\) (for a bulb, brightness depends on power).

Step 2: Effect of Adding a Bulb in Parallel

• When adding a bulb in parallel, the total resistance of the circuit decreases (since \( \frac{1}{R_{\text{total}}} = \frac{1}{R_1} + \frac{1}{R_2} + \dots \)), but the voltage across each existing bulb remains equal to the source voltage (because in parallel, \( V_{\text{bulb}} = V_{\text{source}} \)).
• Since \( P = \frac{V^2}{R} \) and \( V \) and \( R \) for existing bulbs don’t change, their power (and thus brightness) remains the same.

Answer:

All of the bulbs stayed the same brightness (assuming the extra bulb is added in parallel; if series, the answer would differ, but the context implies parallel for this option to be correct). So the correct option is the one stating "All of the bulbs stayed the same brightness".