Presentation is loading. Please wait.

Presentation is loading. Please wait.

Quick Quizzes Direct Current. QUICK QUIZ 18.1 When a piece of wire is used to connect points b and c in this figure, the brightness of bulb R 1 (a) increases,

Similar presentations


Presentation on theme: "Quick Quizzes Direct Current. QUICK QUIZ 18.1 When a piece of wire is used to connect points b and c in this figure, the brightness of bulb R 1 (a) increases,"— Presentation transcript:

1 Quick Quizzes Direct Current

2 QUICK QUIZ 18.1 When a piece of wire is used to connect points b and c in this figure, the brightness of bulb R 1 (a) increases, (b) decreases, or (c) stays the same. The brightness of bulb R 2 (a) increases, (b) decreases, or (c) stays the same.

3 QUICK QUIZ 18.1 ANSWERS R 1 becomes brighter. Connecting a wire from b to c provides a nearly zero resistance path from b to c and decreases the total resistance of the circuit from R 1 + R 2 to just R 1. Ignoring internal resistance, the potential difference maintained by the battery is unchanged while the resistance of the circuit has decreased. The current passing through bulb R 1 increases, causing this bulb to glow brighter. Bulb R 2 goes out because essentially all of the current now passes through the wire connecting b and c and bypasses the filament of Bulb R 2.

4 QUICK QUIZ 18.2 With the switch in this circuit (figure a) closed, no current exists in R 2 because the current has an alternate zero-resistance path through the switch. Current does exist in R 1 and this current is measured with the ammeter at the right side of the circuit. If the switch is opened (figure b), current exists in R 2. After the switch is opened, the reading on the ammeter (a) increases, (b) decreases, (c) does not change.

5 QUICK QUIZ 18.2 ANSWER (b). When the switch is opened, resistors R 1 and R 2 are in series, so that the total circuit resistance is larger than when the switch was closed. As a result, the current decreases.

6 QUICK QUIZ 18.3 With the switch in this circuit (figure a) open, there is no current in R 2. There is current in R 1 and this current is measured with the ammeter at the right side of the circuit. If the switch is closed (figure b), there is current in R 2. When the switch is closed, the reading on the ammeter (a) increases, (b) decreases, or (c) remains the same.

7 QUICK QUIZ 18.3 ANSWER (a). When the switch is closed, resistors R 1 and R 2 are in parallel, so that the total circuit resistance is smaller than when the switch was open. As a result, the total current increases.

8 QUICK QUIZ 18.4 You have a large supply of lightbulbs and a battery. You start with one lightbulb connected to the battery and notice its brightness. You then add one lightbulb at a time, each new bulb being added in parallel to the previous bulbs. As the lightbulbs are added, what happens (a) to the brightness of the bulbs? (b) to the current in the bulbs? (c) to the power delivered by the battery? (d) to the lifetime of the battery? (e) to the terminal voltage of the battery? Hint: Do not ignore the internal resistance of the battery.

9 QUICK QUIZ 18.4 ANSWERS (a) The brightness of the bulbs decreases (b) The current in the bulbs decreases (c) The power delivered by the battery increases (d) The lifetime of the battery decreases (e) The terminal voltage of the battery decreases


Download ppt "Quick Quizzes Direct Current. QUICK QUIZ 18.1 When a piece of wire is used to connect points b and c in this figure, the brightness of bulb R 1 (a) increases,"

Similar presentations


Ads by Google