Exam 24: Capacitors

Consider a capacitor that consists of two parallel plates,one of which can move relative to the other.Air fills the space between the plates,the capacitance is 45.2 pF when the separation between plates is d = 0.360 cm.A battery with potential difference V=12.0 V is connected to the plates to fully charge them and then it is disconnected from the plates.The plates are moved to a separation of 0.180 cm.What is the potential difference V' between the plates now?

An uncharged parallel plate capacitor with an air gap is connected to a 6.0-V battery.After charging,the energy stored in the capacitor is 40 nJ.Without disconnecting the capacitor from the battery,a dielectric material is inserted into the air gap and an additional 200 nJ of energy flows from the battery to the capacitor.What is the dielectric constant of the material?

A 0.2-mF capacitor is charged with 4 $\mu$ C positive on one plate and 4 $\mu$ C negative on the other.What is the voltage (V)on the capacitor?

An air-filled parallel plate capacitor is connected to a battery of voltage V_o.There is charge Q_o on each plate,energy U_o stored between the plates and an electric field of E_o between the plates.The capacitor remains connected to the battery and a dielectric material with a dielectric constant of K is then placed between the plates of the capacitor.What are the new values of V,Q,U,and E? V Q U E

If I want to build a parallel plate capacitor with capacitance 1 F,with a distance of 1 mm between the plates,and the gap filled with glass (dielectric constant 10.0),I would have to use square plates of side length

In circuit shown two identical parallel plate capacitors are connected.Initially the space between the plates of each capacitor is filled with air.If we wish to double the total amount of charge stored on both capacitors for the same applied voltage,which material should we use to fill the space between the plates?

A capacitor consists of two circular parallel plates with diameter D.The plate separation is d,and there is a dielectric with constant k between the plates? Which of the following will double the capacitance.

Capacitors connected in parallel always have the same

A potential difference of V=80.0V is applied across two capacitors in series,with capacitances 17.0 nF and 8.00 nF.What is the charge on the 17.0 nF capacitor?

A point charge of 10 $\mu$ C is surrounded by water (dielectric constant = 80).What is the electric field 0.2 m away?

A single parallel plate capacitor is constructed from two plates that have different areas.If this capacitor is initially uncharged and then connected to a battery,how will the amount of charge on the big plate compare to the amount of charge on the small plate?

High frequency signals are often transmitted along a coaxial cable,which consists of a wire surrounded by an outer grounded conductor.An insulating material fills the space between them and a plastic coating goes around the outside.For one such coaxial cable the radius of the inner wire is 0.5 mm and the radius of the outer conductor is 2.5 mm.The dielectric medium of constant $\kappa$ = 3.7 fills the space between the two conductors.The capacitance per unit length of this coaxial cable is

Consider a capacitor that consists of two parallel plates,one of which can move relative to the other.Air fills the space between the plates,the capacitance is 45.2 pF when the separation between plates is d = 0.360 cm.A battery with potential difference V=12.0 V is connected to the plates to fully charge them and then it is disconnected from the plates.The plates are moved to a new separation,d' and as a result the new potential difference V' between the plates is 10.0 V.What is the new plate separation,d'?

Two capacitors C₁ = 2.5 mF and C₂ = 5.0 mF are connected in series.If a voltage of V = 120 volts is applied across the capacitors,what is the energy stored in the capacitors?

Ventricular fibrillation is a condition of heart dysfunction that can cause death.Under this condition,the heart quivers in an uncoordinated fashion as opposed to beating regularly.An electric shock to the chest can cause momentary paralysis of the heart muscle,after which the heart sometimes starts organized beating again.A defibrillator is a device that applies a strong electric shock to the chest over a few milliseconds.The device is a simple capacitor of several microfarads,charged to several thousand volts.Electrodes called paddles,about 8 cm across and coated with conducting paste,are held against the chest on both sides of the heart.Assume that one such defibrillator has capacitance of 25 µF and is charged to 4,200 Volts.If the capacitor completely discharges in 3.0 ms,the average power delivered to the chest by the defibrillator is

A 2.0-nF parallel plate capacitor with a sheet of mylar (k = 3.1)filling the space between the plates is charged to a potential difference of 90 V and is then disconnected.What is the potential difference between the plates of the capacitor once the mylar is completely removed?

The equivalent capacitance for the three capacitors shown is

A potential difference of V=80.0V is applied across two capacitors in series,with capacitances 17.0 nF and 8.00 nF.What is the magnitude of the electric potential across the 17.0 nF capacitor?

A potential difference of V=24.0 V is applied across two capacitors in parallel,with capacitances 36.0 nF and 48.0 nF.What is the magnitude of the charge on one of the plates of the 36.0-nF capacitor?

An air gap capacitor is charged up to 10 V and then disconnected.If a material is added to the gap between the plates and the voltage drops to 3.33 V,what is the dielectric constant of that material?