Practice: A cardiac defibrillator can be modeled as a parallel plate capacitor. When it is charged to a voltage of 2 kV, it has a stored energy of 1 kJ. What is the capacitance of the defibrillator?

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Capacitors & Capacitance | 8 mins | 0 completed | Learn |

Parallel Plate Capacitors | 20 mins | 0 completed | Learn Summary |

Energy Stored by Capacitor | 16 mins | 0 completed | Learn |

Capacitance Using Calculus | 8 mins | 0 completed | Learn |

Combining Capacitors in Series & Parallel | 16 mins | 0 completed | Learn |

Solving Capacitor Circuits | 29 mins | 0 completed | Learn |

Intro To Dielectrics | 18 mins | 0 completed | Learn Summary |

How Dielectrics Work | 3 mins | 0 completed | Learn |

Dielectric Breakdown | 5 mins | 0 completed | Learn |

Concept #1: Energy Stored by Capacitor

That should be 10^{−6} m^{3}, not just meters. (The number's right, the exponent on the unit is missing.)

Practice: A cardiac defibrillator can be modeled as a parallel plate capacitor. When it is charged to a voltage of 2 kV, it has a stored energy of 1 kJ. What is the capacitance of the defibrillator?

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Concept #1: Energy Stored by Capacitor

Practice #1: Capacitance of Defibrillator

Example #1: Energy Released by Flashbulb

A 4-μF capacitor has a potential drop of 20 V between its plates. The electric potential energy stored in this capacitor is:
A) 80 μJ
B) 8 μJ
C) 8000 μJ
D) 800 μJ

A parallel-plate capacitor is connected to a battery and allowed to charge up. Now the battery is disconnected from the capacitor. The separation between the two plates is now decreased (the plates get closer together). What can we say about the potential energy stored by the capacitor?
A) The potential energy increases
B) The potential energy decreases
C) The potential energy remains the same
D) Unable to determine from the information given.

A 4-μF capacitor has a potential drop of 20 V between its plates. The electric potential energy stored in this capacitor is:
A) 8 μJ
B) 8000 μJ
C) 80 μJ
D) 800 μJ

In open-heart surgery a small amount of energy will defibrillate the heart.(a) What voltage is applied to the 8.59 μF capacitor of a heart defibrillator that stores 44.8 J of energy? ________KV (b) Find the amount of stored charge. ________mC

Two batteries (in series), a bulb, an uncharged capacitor, and a switch are connected together in a circuit with the switch open. (Note, the positive end of the battery is connected to the positive terminal of the capcitor) 1. what happens to the current in this circuit and the voltage across the bulb after the switch is closed? (Do they increase or decrease) How do your answers to question relate to the presence of the capacitor in the circuit?2. What happens to the voltage across the capacitor over time when starting with a partially-charged capacitor? Why? 3. If you re-ran the lightbulb-timing experiment, except you started with a partially-charged capacitor, what would be different and why?

Suppose a parallel plate capacitor (with capacitance C0) is fully charged (to a value Q0) by a battery. The battery (which supplies a potential difference of V0) stays connected to the capacitor. If the plates of the capacitor are then moved closer together (the separation distance d between the plates is halved), describe quantitatively what happens to: a) the capacitance of the capacitor. b) the potential difference between the plates. c) the energy stored in the capacitor. d) the charge on the plates.

Two 3.00 cm × 3.00 cm plates that form a parallel-plate capacitor are charged to± 0.708 nCA)What is the electric field strength inside the capacitor if the spacing between the plates is 2.60 mm ?Express your answer with the appropriate units.B)What is the potential difference across the capacitor if the spacing between the plates is 2.60 mm ?Express your answer with the appropriate units.

Two 3.00 cm × 3.00 cm plates that form a parallel-plate capacitor are charged to ± 0.708 nCA) What is the electric field strength inside the capacitor if the spacing between the plates is 1.30 mm ? Express your answer with the appropriate units.B) What is potential difference across the capacitor if the spacing between the plates is 1.30 mm ?Express your answer with the appropriate units.

Consider the case when the constant A = 3 and the time constant, τ = 4. Plot the graph of y = 3e-t/4. Make it a position versus time graph.

Storm clouds build up large negative charges, as described in the chapter. The charges dwell in charge centers, regions of concentrated charge. Suppose a cloud has -25 C in a 1.0-km-diameter spherical charge center located 10 km above the ground, as sketched in the figure. The negative charge center attracts a similar amount of positive charge that is spread out on the ground below the cloud.The charge center and the ground function as a charged capacitor, with a potential difference of approximately 4 x 108 m The large electric field between these two "electrodes" may ionize the air, leading to a conducting path between the cloud and the ground. Charges will flow along this conducting path, causing a discharge of the capacitor - a lightning strike.1) What is the approximate magnitude of the electric field between the charge center and the ground?A) 4 x 104 V/m B) 4 x 105 V/mC) 4 x 106 V/m D) 4 x 107 V/m2) What is the approximate capacitance of the charge center-ground system?A) 6 x 10-8 FB) 2 x 107 FC) 4 x 106 FD) 8 x 106 F3) If the cloud transfers all of its charge to the ground via several rapid lightning flashes lasting a total of 1.90 s, what is the average power?A) 12.7 GWB) 3.74 GWC) 2.74 GWD) 1.74 GW

Capacitor 2 has half the capacitance and twice the potential difference as capacitor 1. What is the ratio Uc1/Uc2.

Part A. Find the energy U0 stored in the capacitor. Express your answer in terms of A, d, V, and ϵ0.Part B. The capacitor is now disconnected from the battery, and the plates of the capacitor are then slowly pulled apart until the separation reaches 3d. Find the new energy U1 of the capacitor after this process.Express your answer in terms of A, d, V, and ϵ0.Part C. The capacitor is now reconnected to the battery, and the plate separation is restored to d. A dielectric plate is slowly moved into the capacitor until the entire space between the plates is filled. Find the energy U2 of the dielectric-filled capacitor. The capacitor remains connected to the battery. The dielectric constant is K.Express your answer in terms of A, d, V, K, and ϵ0.

In open-heart surgery, a small amount of energy will defibrillate the heart. (a) What voltage is applied to the 8.28 μF capacitor of a heart defibrillator that stores 42.3 J of energy? _________ kV(b) Find the amount of stored charge._________ mC

You have two identical capacitors and an external potential source.Compare the total energy stored in the capacitors when they are connected to the applied potential in series and in parallel.U(parallel)/U(series) =?

A capacitor consists of two 7.0-cm-diameter circular plates separated by 1.0 mm. The plates are charged to 160 V , then the battery is removed.1) How much energy is stored in the capacitor?2) How much work must be done to pull the plates apart to where the distance between them is 2.0 mm?

You have two capacitors, one is 6.0 μF the other is 3.0 μF. You also have some wires and a 9.0 V battery. Determine the total energy stored by the capacitors when a) Connected in parallel and b) connected in series. Which configuration has greater energy?

Suppose you have a 9.00-V battery, a 2.00-μF capacitor, and a 7.40-μF capacitor Find the charge and energy stored if the capacitors are connected to the battery in parallel

Suppose you have a 9.00-V battery, a 2.00-μF capacitor, and a 7.40-μF capacitor Find the charge and energy stored if the capacitors are connected to the battery in series. .

A large capacitor has a charge +q on one plate and -q on the other. At time t=0, the capacitor is connected in series to two ammeters and a light bulb. Immediately after the circuit is closed, the ammeter connected to the positive plate of the capacitor reads IP and the ammeter connected to the negative plate of the capacitor reads IN. (Figure 1)Each ammeter reads positive if current flows through the circuit in a clockwise direction (from the + to the – terminal of the meter).Immediately after time t = 0, what happens to the charge on the capacitor plates?Check all that apply.a. Individual charges flow through the circuit from the positive to the negative plate of the capacitor.b. Individual charges flow through the circuit from the negative to the positive plate of the capacitor.c. The positive and negative charges attract each other, so they stay in the capacitor.d. Current flows clockwise through the circuit.e. Current flows counterclockwise through the circuit.

Given a parallel-plate capacitor with plates of area A separated by a distance l. Consider the quantities, (i) capacitance C, (ii) magnitude E of the electric field between the plates, (iii) magnitude of the charge Q on the plates, (iv) potential difference ΔV between the plates, and (v) energy U stored in the capacitorAssume we apply a given potential difference ΔV0 to the plates. Suppose we double the plate separation while keeping the potential difference constant, calculate the quantities (i) - (v), for this case, and express each in terms of the original value, e.g., C = 2C0, E = (1/4)E0, etc. (Obviously, ΔV = ΔV0).

Given a parallel-plate capacitor with plates of area A separated by a distance l. Consider the quantities, (i) capacitance C, (ii) magnitude E of the electric field between the plates, (iii) magnitude of the charge Q on the plates, (iv) potential difference ΔV between the plates, and (v) energy U stored in the capacitorAssume we apply a given potential difference ΔV0 to the plates. Suppose we had double the plate separation while keeping the charge on the plates constant. Calculate the quantities (i) - (v) for this case, and express each in terms of its original value. (Obviously, Q = Q0).

Given a parallel-plate capacitor with plates of area A separated by a distance l. Consider the quantities, (i) capacitance C, (ii) magnitude E of the electric field between the plates, (iii) magnitude of the charge Q on the plates, (iv) potential difference ΔV between the plates, and (v) energy U stored in the capacitorAssume we apply a given potential difference ΔV0 to the plates.Suppose we had not changed the geometry of the capacitor but had filled the space between the plates with a dielectric of dielectric constant, K while keeping the charge Q on the pates unchanged. How would that affect the quantities (i) - (v)?

Given a parallel-plate capacitor with plates of area A separated by a distance l. Consider the quantities, (i) capacitance C, (ii) magnitude E of the electric field between the plates, (iii) magnitude of the charge Q on the plates, (iv) potential difference ΔV between the plates, and (v) energy U stored in the capacitorAssume we apply a given potential difference ΔV0 to the plates.Suppose we had not changed the geometry of the capacitor but had filled the space between the plates with a dielectric of dielectric constant, K but instead of keeping Q constant we keep the potential difference ΔV0 constant. How would that affect the quantities (i) - (v)?

Given a parallel-plate capacitor with plates of area A separated by a distance l. Consider the quantities, (i) capacitance C, (ii) magnitude E of the electric field between the plates, (iii) magnitude of the charge Q on the plates, (iv) potential difference ΔV between the plates, and (v) energy U stored in the capacitorAssume we apply a given potential difference ΔV0 to the plates. In terms of any of A, l, ΔV0, and constants express each of the quantities (i) - (v) listed above. Use subscripts "0" for each result: C0, E0, etc.

A pair of 10μF capacitors in a high-power laser are charged to 1.7 kV.a. What charge is stored in each capacitor?b. How much energy is stored in each capacitor?

A parallel-plate air capacitor has a capacitance of 920 pF. The charge on each plate is 3.90 μC. Part AWhat is the potential difference between the plates? Express your answer with the appropriate units. Part B If the charge is kept constant, what will be the potential difference between the plates if the separation is doubled? Express your answer with the appropriate units. Part C How much work is required to double the separation? Express your answer with the appropriate units (mJ)

Consider a parallel-plate capacitor with plates of area A and with separation d. Find F(V), the magnitude of the force each plate experiences due to the other plate as a function of V, the potential drop across the capacitor. Express your answer in terms of given quantities and ϵ0.

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