AP Physics LC Circuits

The figure shows three identical lightbulbs connected to a battery having a constant voltage across its terminals. What happens to the brightness of lightbulb 1 when the switch S is closed?

• The brightness will increase momentarily then return to its previous level.

• The brightness increases permanently.

• The brightness will decrease momentarily then return to its previous level.

• The brightness remains the same as before the switch is closed.

• The brightness decreases permanently.

In the circuit shown in the figure, all the lightbulbs are identical. Which of the following is the correct ranking of the brightness of the bulbs?

• B and C have equal brightness, and A is the dimmest.

• A is brightest, C is dimmest, and B is in between.

• A and B have equal brightness, and C is the dimmest.

• A is the brightest, and B and C have equal brightness but less than A.

• All three bulbs have the same brightness.

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-5

A light bulb is connected in the circuit shown in the figure with the switch S open. All the connecting leads have no appreciable resistance and the battery has no internal resistance. When we close the switch, which statements below accurately describe the behavior of the circuit? (There may be more than one correct choice.)

• The brightness of the bulb will increase.

• The brightness of the bulb will decrease.

• The brightness of the bulb will not change.

• The potential drop across R2 will decrease.

• The potential drop across R2 will not change.

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

A resistor and a capacitor are connected in series across an ideal battery having a constant voltage across its terminals. At the moment contact is made with the battery, the voltage across the capacitor is

• equal to the battery's terminal voltage.

• less than the battery's terminal voltage, but greater than zero.

• zero.

A resistor and a capacitor are connected in series across an ideal battery having a constant voltage across its terminals. At the moment contact is made with the battery the voltage across the resistor is

• equal to the battery's terminal voltage.

• less than the battery's terminal voltage, but greater than zero.

• zero.

An RC circuit is connected across an ideal DC voltage source through an open switch. The switch is closed at time t = 0 s. Which of the following statements regarding the circuit are correct? (There may be more than one correct choice.)

• The capacitor charges to its maximum value in one time constant and the current is zero at that time.

• The potential difference across the resistor and the potential difference across the capacitor are always equal.

• The potential difference across the resistor is always greater than the potential difference across the capacitor.

• The potential difference across the capacitor is always greater than the potential difference across the resistor

• Once the capacitor is essentially fully charged, there is no appreciable current in the circuit.

A light bulb is connected in the circuit shown in the figure with the switch S open and the capacitor uncharged. The battery has no appreciable internal resistance. Which one of the following graphs best describes the brightness B of the bulb as a function of time t after closing the switch?

• 
• 
• 
• 
• 

A wire of resistivity ρ must be replaced in a circuit by a wire of the same material but 4 times as long. If, however, the resistance of the new wire is to be the same as the resistance of the original wire, the diameter of the new wire must be

• 2 times the diameter of the original wire.

• 4 times the diameter of the original wire.

• the same as the diameter of the original wire.

• 1/2 the diameter of the original wire.

• 1/4 the diameter of the original wire.

Which resistor is in series with resistor R?

• R₁

• R₂

• R₃

• R₄

The two ends of a 3.0-ohm resistor are connected to a 9.0-V battery. What is the current through the resistor?

• 27 A

• 6.3 A

• 3.0 A

• 0.33 A