Changing the dielectric causes the capacitance to change.
If the slab is zero thickness, nothing. The lines of electric field not intercepted by the slab are unaffected, so what goes on there is unaffected. The part where the lines are intercepted is converted to two capacitors in series, and the charges on opposite sides of the slab are equal and opposite, equal to the charge on the parts original outer plates facing it. From the outside view of the world, nothing changes on the outer plates, so the capacitance is the same. If the plate is not zero thickeness, then the capacitors on that side become higher and so the total capacitance will increase, with significant distortions of field lines. <<>> For a parallel-plate capacitor with small spacing, so that fringing can be neglected, with a flat slab of dielectric, the new capacitance is easily calculated by noting that the electric flux D is continuous, and in the volume occupied by the dielectric the E-field is reduced by a factor equal to the relative permittivity. Thus the voltage is reduced for a given amount of charge and the capacitance increased. If the plate area is A and the spacing is s and the dielectric thickness d, then with a charge Q on the plates the electric flux is just D = Q/A. The electric field on a line between the plates is D/eps0 in the air and D/(eps0 x epsr) inside the dielectric. Therefore the voltage is D/eps0 x (s-d) from the two air paths plus D/(eps0 x epsr) x d from the dielectric path. So the capacitance in this case is given by: C = A x eps0 / [s - d(1 - 1/epsr)] So if d=0 or epsr=1, as they are when there is no dielectric, the capacitance reverts to the standard formula for parallel plates: C = A x eps0 / s
For an insulating material dielectric strength and dielectric loss should be respectively
The dielectric,usually the insulator between the plates of a capacitor, can be overstressed by the application of too high voltages applied to the capacitor plates. The dielectric breaks down and a current flows between the plates until,either they are discharged, or an equilibrium is reached,below the working voltage of the capacitor. If the dielectric is damaged in this process he capacitor must be replaced. Some dielectric material self heal and can recover from an over voltage.
Capacitors are named after their dielectrics. So, an 'air capacitor' uses air as its dielectric, a 'mica capacitor' uses mica as its dielectric, and so on. There are lots of different dielectric used to separate the plates of a capacitor, each with different permittivities and dielectric strengths. As the perfect dielectric (i.e. one with both a very high permittivity and a very high dielectric strength) doesn't occur, the choice of dielectric is always a compromise between it permittivity and dielectric strength.
Changing the dielectric causes the capacitance to change.
(a) Charge Will increase (b) Potential difference will stay the same (c) Capacitance will increase (d) Stored energy will decrease
Johannes Jacobsen has written: 'Analytical, numerical and experimental investigation of guided waves on a periodically, strip-loaded dielectric slab' -- subject(s): Antennas (Electronics)
the charge on the capacitor had increased.
If the slab is zero thickness, nothing. The lines of electric field not intercepted by the slab are unaffected, so what goes on there is unaffected. The part where the lines are intercepted is converted to two capacitors in series, and the charges on opposite sides of the slab are equal and opposite, equal to the charge on the parts original outer plates facing it. From the outside view of the world, nothing changes on the outer plates, so the capacitance is the same. If the plate is not zero thickeness, then the capacitors on that side become higher and so the total capacitance will increase, with significant distortions of field lines. <<>> For a parallel-plate capacitor with small spacing, so that fringing can be neglected, with a flat slab of dielectric, the new capacitance is easily calculated by noting that the electric flux D is continuous, and in the volume occupied by the dielectric the E-field is reduced by a factor equal to the relative permittivity. Thus the voltage is reduced for a given amount of charge and the capacitance increased. If the plate area is A and the spacing is s and the dielectric thickness d, then with a charge Q on the plates the electric flux is just D = Q/A. The electric field on a line between the plates is D/eps0 in the air and D/(eps0 x epsr) inside the dielectric. Therefore the voltage is D/eps0 x (s-d) from the two air paths plus D/(eps0 x epsr) x d from the dielectric path. So the capacitance in this case is given by: C = A x eps0 / [s - d(1 - 1/epsr)] So if d=0 or epsr=1, as they are when there is no dielectric, the capacitance reverts to the standard formula for parallel plates: C = A x eps0 / s
For an insulating material dielectric strength and dielectric loss should be respectively
dielectric constant
For an insulating material dielectric strength and dielectric loss should be respectively high or low
why need dielectric test for transformer
The dielectric,usually the insulator between the plates of a capacitor, can be overstressed by the application of too high voltages applied to the capacitor plates. The dielectric breaks down and a current flows between the plates until,either they are discharged, or an equilibrium is reached,below the working voltage of the capacitor. If the dielectric is damaged in this process he capacitor must be replaced. Some dielectric material self heal and can recover from an over voltage.
Supended slab are slab not sit on the ground directlySuspended slab is a slab supported by beams.
Capacitors are named after their dielectrics. So, an 'air capacitor' uses air as its dielectric, a 'mica capacitor' uses mica as its dielectric, and so on. There are lots of different dielectric used to separate the plates of a capacitor, each with different permittivities and dielectric strengths. As the perfect dielectric (i.e. one with both a very high permittivity and a very high dielectric strength) doesn't occur, the choice of dielectric is always a compromise between it permittivity and dielectric strength.