Capacitors
Circuits
VIR
Power & Energy
100
When two identical parallel-plate capacitors are connected in series, which is true of the equivalent capacitance?
(A) It depends on the charge on each capacitor
(B) It depends on the potential difference across both capacitors
(C) It is larger than the capacitance of each capacitor
(D) It is smaller than the capacitance of each capacitor
(E) It is the same as the capacitance of each capacitor.
(D) It is smaller than the capacitance of each capacitor
100
What is the value of R?
2 ohms
100
Two wires are made of the same material and have the same length. Wire A is thicker than Wire B. Which wire has the greater resistance?
Wire B
100
A resistor connected to a fixed battery is replaced with a resistor of twice the resistance. What happens to the power dissipated by the resistor?
1/2 of the initial
P=V2/R
200
A capacitor with air between its plates is fully charged with a charge +Qo by connecting to a battery with a constant voltage Vo. After the space between the plates is filled with oil, the difference in potential is V and the charge is Q. Compare the magnitudes of +Q/Q and Vo/V (with >,=,<)
Q > Qo and V = Vo
200
State Kirchhoff's Laws (current and voltage)
sumV=0
^for any loop
sumI=0
^for any junction
200
Four positive charges of magnitude q are arranged at the corners of a square. At the center C of the square, the potential due to one charge alone is Vo, and the electric field due to one charge alone has magnitude Eo. What is the electric potential and the magnitude of the electric field at the center of the square due to all four charges?
4 Vo
E field=0
200
A student claims: “A higher-resistance bulb is always dimmer.” Give a situation where this is NOT true.
If multiple bulbs are in a series circuit, the higher bulb with a higher resistance will be brighter.
P=I2R
300
Two square parallel-plate capacitors of capacitances C1 and C2 have the dimensions
shown. The ratio of C1 to C2 is...
1:2
300
Connecting another light bulb in
parallel with the first bulb as shown by the dashed lines would
(A) increase the ammeter reading
(B) decrease the ammeter reading
(C) increase the voltmeter reading
(D) decrease the voltmeter readig
(E) produce no change in either meter reading
(A) increase the ammeter reading
300
An electron moves from a region of low electric potential to high electric potential. What happens to:
1. It's electric potential energy
2. Its speed?
1. UE decreases
2. Speed increases
U=qV
300
A 5Ω, 8Ω, and 11Ω lightbulbs are connected, both in series and in parallel with a 20V power supply. Which bulb(s) (5Ω, 8Ω, or 11Ω) in which circuit (series or parallel) is/ are the brightest?
5Ω in parallel
400
There is a system of six 2μF capacitors as shown. What potential difference must be applied between points X and Y so that the
charge on each plate of each capacitor will have a magnitude equal to 6 μC?
6V
400
Find the values of the unknown resistors.
R1= 1.5Ω
R2= 3Ω
400
Positive charge Q is uniformly distributed over a thin ring of radius a that lies in a plane
perpendicular to the x-axis with its center at the origin 0, as shown. Write a function to represent V at points along the X axis.
V(x)=(kQ)/sqrt(a^2+x^2)
400
A 20 ohm, 5 watt resistor is placed in series with a power supply.
(a) What is the maximum voltage that can be applied to the resistor without harming the resistor?
(b) what would be the current through the resistor?
(a) 10V
(b) 0.5A