Electrostatic Potential and Capacitance Flashcards
The SI unit of electrical capacitance
Farad
The potential between the plates of a capacitor is constant. A dielectric medium is filled instead of air in between the plates. The intensity of electric field will:
Remains unchanged
On replacing the air by an insulating material between the plates of a capacitor its capacity:
Increases
On increasing the separation between the plates of a parallel plate capacitor its capacitance:
Decreases
When two capacitors are joined in series each capacitor will have the same:
Charge
When two capacitors are joined in parallel each capacitor will have the same
Potential
Two capacitors of equal capacitance first connected in parallel then connected in series. What is the ratio of their capacities in both the cases:
4:1
The formula of capacitances of a spherical conductor is:
C=4πε0R
The angles between equipotential surface and electric lines of force is:
90
1 farad =
one coulomb/volt
1 farad = ______stat farad
9 x 10^11
Dimensional formula of capacitance is
[M^−1 L^−2 T^4 A^2]
______ is a device in which changing the shape or size of a conductor its capacitance can be increased.
Capacitor
On increasing the distance between the plates of a parallel plate capacitor its capacity
Increases
three capacitor each of 3 uF are joined in series there equivalent capacitance will be
1 uF
The dimensional formula of electric potential is
M L^2 T^-3 A^-3
The potential due to a point charge q at a distance r is given by
q x 1 / 4πε0R
the potential diff. = Intensity of electric field x ____________
Distance b/w the two points
The increase in kinetic energy of a charge “q” when it is accelerated by a potential diff. V is
qV
Due to presence of a dielectric medium the potential
Decreases
The work done in moving a charge perpendicular to the electric field is
Zero
The potential of Earth is considered to be
Zero
Formula of capacitance of parallel plate capacitor
ε0A / d
Intensity of electric field inside a hollow conductor =
0
What is net charge on a charged capacitor
Zero
At which position of the dipole , the electric potential die to is will be zero ?
In the equatorial position
When should the capacitors be connected in series ?
When a high potential is to be distributed to several capacitors
When should be the capacitors connected in parallel ?
When capacitance is to be increased
What is the effect of insulated medium on the potential ?
The potential of the conductor decreases
is it possible that at any point the intensity of electric field is zero but potential does not .
Yes, inside the charged hollow conductor.
WORK DONE BY EXTERNAL FORCE IN MOVING CHARGE FROM R TO P
WRe=∫RPFex⋅dr=−∫RPFext⋅dr
DEFINR ELECTROSTATICS POTENIAL
The electrostatic potential, also known as the electric field potential, electric potential, or potential drop is defined as
The amount of work done to move a unit charge from a reference point to a specific point inside the field without producing an acceleration.UNI
UNIT OF ELECTRIC POTENTIAL
volt
ML2T3I-1
POTENTIAL DUE TO POINT CHARGE
V = Q/ 4PI EO R
DEFINE EQUIPOTENTIAL SURFACE
The surface, the locus of all points at the same potential, is known as the equipotential surface
RELATION BETWEEN FIELD AND POTENTIAL
“Electric field is the negative space derivative of electric potential.”
E = -dV/dX
POTENTIAL ENERGY OF Q AT R IN AN EXTERNAL FIELD
QVR
INSIDE CONDUCTOR ELECTROSTATICS FIELD IS
0
AT SURFACE OF CHARGED CONDUCTOR ELECTROSTATICS FIELD MUST BE
NORMAL TO THE SURFACE AT EVERY POINT
ELECTRIC FIELD AT THE SURFACE OF CHARGED CONDUCTOR
E=σε0ˆn.
ELECTROSTATIC SHEILDING
THE FIELD INSIDE CAVITY IS ZERO THIS IS KNOWN AS ELECTROSTATIC SHEILDING
CURRENT PASSES ONLY WHE THERE IS CHANGE IN —
POTENTIAL
DEFINE DIELECTRICS
DIELECTRICS ARE NON CONDUCTING SUBSTANCE
Dielectrics, in general, can be described as materials that are very poor conductors of electric current. They are basically insulators and contain no free electrons.
TYPE OF DIELECTRIC MATERIALS
1] POLAR MOLECULES
2] NON POLAR MOLECULES
DEFINE POLAR MOLECULES
PERMANENT ELECTRIC DIPOLE
ITS POLARZIATION IS TEMP DEPANDENTED
NON POLAR MOLECULES
INDUCED ELECRTIC DIPOLE
ITS POLARSTATION IS INDEPENTED OF TEMP
DEFINE POLARIZATION
Polarisation can thus also be thought of as a phenomenon in which an alignment of positive and negative charges takes place within the dielectric, resulting in no net increase in the charge of the dielectric.
DEIFNE LINEAR ISOTROPIC DIELECTRICS
A linear isotropic dielectric is a dielectric in which the permittivity is a scalar and has equal value at all direction.
P [ POLARISATION ]
P = Xe E
DEFINE Xe
Xe IS CONSTANT CHARACTERSTICS OF DIELECTRIC AND IS KNOWN AS ELECTRIC SUSCEPTBITY OF DIELECTRIC MEDIUM
CAPACTIANCE
C = Q/V = EO A/ d
EFFECT OD DIELECTRIC ON CAPATCIANCE
Capacitors use non-conducting materials, or dielectrics, to store charge and increase capacitance.
CAPACITOR I SERIES
1/C= 1/C1+1/C2….
CAPACITOR IN PARALLEL
C= C1+C2+C3…..
ENERGY STORED IN CAPACITOR
Energy stored in a capacitor is electrical potential energy,ΔPE = qΔV to a capacitor.
FORMULA OF U FOR CAPACITOR
1/2QV = 1/2CV2 = 1/2 Q2/C
