Previous Year Physics Question Papers (with solutions) of Kerala State Syllabus of Higher Secondary Examinations. Chapter Name: ELECTROSTATIC POTENTIAL AND CAPACITANCE
Previous Year Questions of March Examinations from 2010 to 2020
Chapter Name: ELECTROSTATIC POTENTIAL AND CAPACITANCE
One coulomb charge is initially at rest and is accelerated through a potential difference of I volt. During this process the kinetic energy acquired by the charge is (a) 1 J (b) 1.6 x 10 -19 J (c) 1.6 x 1019 J d) 10 J
Capacitors are considered to be the building blocks of all integrated circuits. A Parallel plate capacitor is a simple form of a capacitor. a) Write down the expression for the capacity of a parallel plate air capacitor in terms of plate area and their separation. b) Raju found that capacity of a parallel plate air capacitor is 10 F. Find the capacity of it when he immersed the unit completely in a medium of dielectric constant 2.5. c) Obtain an expression for the energy stored in a capacitor. d) Raju charged this capacitor and he plotted a graph between changing potential and charge stored in the capacitor. The graph is shown in the figure. What does the area of the shaded portion of the graph represent?
a) C =ε0A/d
b) Cm = K C = 2.5 x 10 F
c) Hints
dw = V dq = q/C dq
On integration from 0 to Q
U = W = 1/2 Q2/C = 1/2 CV2
A capacitor is a device used for storing charges as well as energy. It is based on a property called capacitance. a) Write the SI unit of capacitance and define it. b) You are given two capacitors of 2μF and 3 μF. What are the maximum and minimum values of capacitance that can be obtained by combining them? c) Obtain an expression for the electrostatic energy stored in a capacitor
a) Farad b) Maximum = 5μF Minimum = 5/6 μF c) Hints
dw = V dq = q/C dq
On integration from 0 to Q
U = W = 1/2 Q2/C = 1/2 CV2
Besides its use in storing charge, a capacitor is a key element of most a.c circuits a) What are the factors on which the capacitance of a parallel plate air capacitor depends? b) Define the term ‘dielectric constant’ of a medium. c) Two capacitors C1 and C2 are connected in series. Derive an expression for the capacitance of the combination. d) Find the equivalent capacitance of capacitors given in the network.
a) Area of the plate, seperation between the plates and the nature of the material between the plates
b) K = F0 / Fm = C / C0
c) Voltage divides, charge same
d) Cab = 16μF
Cbc = 9μF
and C = 1μF
Capacitor is an arrangement to increase the charge carrying capacity of a conductor a) Each plate of a parallel plate capacitor has a charge q on it. The capacitor is now connected to a battery. Pick out the correct statement/statements: i) The facing surface of the plates have equal and opposite charges ii) The battery supplies equal and opposite charges to the two plates iii) The two plates of the capacitor have equal and opposite charges b) The plates of a parallel plate capacitor each of area A is charged with charges +Q and –Q. Deduce the force acting between the plates of the capacitor c) Van De Graaff generator is a high voltage generator used to accelerate charged particles. Draw a labelled schematic diagram of a Van De Graaff generator and state the principle behind its working
a) i) True ii) True iii) True b) Hints
Energy U = F d
U = 1/2 Q2/C
C = ε0A/d c) If the charged conductor is brought in to internal contact with a hollow conductor, charges are transfered to the surface of the hollow conductor no matter how high the potential of the latter (inner) may be
“Gauss”s law is true for any closed surface, no matter what its shape or size” say the following statements are true or false. a) Gauss”s law implies that the total electric flux through a closed surface is zero if no charge is enclosed by the surface b) This law is useful for the calculation of electrostatic field when the system does not possess any symmetry c) In a uniform electric field, we know that the dipole experiences no net force; but experiences a torque having a relation with P and E is given by .......
, where the parameters P and E have their usual meaning
(A) A device to store electric charge is called (a) Transformer (b) Capacitor (c) Resistor (d) Inductor (B) What is meant by energy density of a capacitor? (C) Derive an expression for the energy stored in a parallel plate capacitor (D) What is the area of plates of a 0.1μF parallel plate air capacitor, given that the separation between the plates is 0.1mm?
(A) Capacitor (B) Energy stored in a Capacitor in unit volume (C) Hints
dw = V dq = q/C dq
On integration from 0 to Q
U = W = 1/2 Q2/C = 1/2 CV2 (D) Area = 1.12 m2
An equipotential surface is a surface with constant value of potential at all points on the surface
(a) What is the amount of work done in moving a 2 μ c charge between two points at 3 cm apart on an equipotential surface?
(b) Two capacitors are connected as shown in figure
If the equivalent capacitance of the combination is 4 μ F (i) Calculate the value of C (ii) Calculate the charge on each capacitor (iii) What will be the potential drop across each capacitor? (c) Two metallic spheres of same radii, one hollow and one solid, are charged to the same potential. Which will hold more charge? (i) Solid sphere (ii) Both will hold same charge (iii) Hollow sphere (iv) Cannot predict
(a) Zero (b) i) C = 5 μF ii) 48 μC charge on each capacitor iii) 2.4 V on 20 μF and 9.6 V on 5 μF c) Both will hold same charge
(a) A dielectric slab is placed between the plates of a parallel plate capacitor. Its capacitance (i) becomes zero (ii) remains the same (iii) decreases (iv) increases (b) Derive an expression for energy stored in a capacitor
The electric field lines of a positive charges is as shown in figure (а) Give the sign of potential difference VP - VQ (b) Give the sign of work done hy the field in moving a small psitive charge from Q to P (c) What is the shape of equipotential surface near the charge
The equipotential surface through a point is normal to the electric field at that point. (a) What is meant by equipotential surface ? (b) What is the work done to move a charge on an equipotential surface ? (c) Draw the equipotential surfaces for a uniform electric field.
(a) An equipotential surface is a surface with a constant value of potential at all points on the surface (b) Workdone to move a charge on an equipotential surface is Zero (c) Equipotential is Plane for Uniform Electric Field
How capacitance changes if the distance between the plates of a parallel plate capacitor
is halved ? (a) Does not change (b) Becomes half (c) Doubled (d) Becomes one fourth
Three capacitors of capacitances 2 pF, 3 pF and 4 pF are connected in parallel. (a) Write the SI unit of capacitance. (b) Calculate the effective capacitance of the combination. (c) Determine the charge on each capacitor if the combination is connected to a 100 V supply.
(a) Farad (b) Cp = C1 +C2 + C3 = 9pF
OR
In Series
Cs = (12/13) pF (c)
Q1 = C1V = 2 x 10 -10 C
Q2 = C2V = 3 x 10 -10 C
Q3 = C3V = 4 x 10 -10 C
OR
In Series
Q = 12/13 x 10 -10 C
