Which of the following sequences explains how to charge an electroscope by induction using a plastic rod that has been rubbed with fur?
Answer
Touch plastic rod to metal sphere on the top of the electroscope, then remove it.
Touch metal sphere of electroscope with finger to ground it. Bring charged plastic rod near metal sphere without touching it. Remove rod then remove finger.
Bring charged plastic rod near the metal sphere of electroscope without touching it. Briefly touch the sphere with finger to ground it. Remove finger, then remove charged rod.
Touch metal sphere of electroscope with finger to ground it. Touch charged plastic rod to metal sphere of electroscope. Remove both at same time.
Question 2
Question
The two plates of a parallel plate capacitor in a circuit have a charge that is equal in magnitude but opposite sign in sign because:
Answer
One plate becomes negatively charged from the battery. The other plate polarizes, driving negative charge away from that plate.
Current flows through both plates. After electrons are used up moving through the 1st plate, the 2nd plate is left positive.
Electrons from the battery are stopped by one plate, giving the plate a positive charge. The other plate polarizes to be negative.
Electron current flows one way out of the battery, setting up a negative charge on one plate. Proton current flows out the other end of the battery setting up a positive charge on the other plate.
Question 3
Question
A capacitor is placed in a circuit and allowed to charge.
After a long time, why does the current stop flowing in the circuit? (Select 2 answers)
Answer
Electric potential across the capacitor acts like a battery in the opposite direction.
Electrons discharge out of the circuit.
Current becomes slower as protons are stored on the capacitor plates.
Negative charges on the capacitor repel the electron current from the battery.
Question 4
Question
A student builds two series circuits. The relative values of capacitance (C), resistance (R) and battery potential (V) of the two circuits is listed below:
Circuit 1: Capacitor C, Resistor R, Battery V.
Circuit 2: Capacitor 2C, Resistor R/2, Battery 2V.
Which of the following statements is true? (Select 2 answers)
Answer
The capacitor in Circuit 1 will charge faster than the capacitor in Circuit 2.
The capacitors in both circuits will charge in the same amount of time.
The capacitors in both circuits will reach the same maximum potential difference.
The capacitor in Circuit 2 will reach a higher maximum potential difference.