Download Physics Work Sheet 2

Class XII Physics
WORK SHEET -2 Ch-2
1 marks based questions---Q1- the graph in the figure shows the variation of charge Q with voltage V for two capacitors K and L. In which
capacitor is ore electrostatic energy stored?
Q2- Define dielectric constant in terms of the capacitance of a capacitor.
Q3- The electric field induced in a dielectric placed in an external field 1/8 times the external field. Calculate
relative permittivity o the dielectric.
Q4- A hollow metal sphere of radius 5cm is charged such that the potential on its surface is 10V. What is the
potential at the centre of the sphere?
Q5- The plot of the variation of potential difference across a combination of three identical cells in series
versus current is shown in figure. What is the emf of each cell?
6 V

1A
Q6- explain the role of earthing in household wiring?
2 marks based questions----Q1- What happens to the capacitace of the capacitor when a copper plate of thickness 1/3rd of the separation
between the plates is introduced in the capacitor?
Q2- A parallel plate of capacitor of capacitance C is charged to a potential V. It is then connected to another
uncharged capacitor having the same capacitance. Find the ratio of the energy stored in the combined system
to that stored initially in the single capacitor.
Q3- Net capacitance of three identicle capacitors in series is 1 micro farad. What will be their net capacitance
if connected in parallel? Fnd the ratio of energy stored I two configuration if they are both connected to the
same source.
Q4- Two capacitors of capacitances 6 micro farad and 12 micro farad are connected in series with a battery.
The voltage across the 6 micro farad capacitor is 2V. Compute the battery voltage.
Q5- Two point charges 4 micro coulomb and -2 micro coulomb are separated by a distance of 1m in air.
Calculate at what point on the line joining the two charges is the electric potential is zero.
3 marks based questions-------Q1- Find an expression for the capacitance of parallel plate capacitor having dielectric medium filed between
the plates.
Q2- Find the expression for the potential energy of a charged capacitor. Where does this energy reside obtain
the formula for energy density.
Q3- On charging a parallel plate capacitor to a potential V, the spacing between the plates is halved and a
dielectric medium of Er = 10 is introduced between the plates, without disconnecting the DC source. Explain,
using suitable expressions, how????
I)
II)
III)
The capacitance.
Electric field.
Energy density of the capacitor changes?
Q4- For any charge distribution equipotential surface through a point is normel to the electric field – justify.
Q5- A test charge q is moved without acceleration from A to C along the path from A to B and then from B to C
in Electric field E as shown in figure.
I)
II)
Calculate the potential difference between A and C.
At what point of the two is electric potential more and why?
B(-2,2)
E
C (-2,-1)
A(2,-1)
Q6- Draw the equipotential surface due to an electric dipole. Locate the points where potential due to the
dipole is 0.
4 Marks based questions------Q1- Kshitij and Dhruva the two brothers were travelling in a car during a heavy thunderstorm. They see the
children of a village primary school are enjoying the rain in an open ground and teachers are watching them
sitting under a Pipal tree in the middle of the ground . they request them to go inside the school building
school whose doors , walls and roof were constructed from metal sheets (tin sheets) insulated from inside , to
save them from a probable natural calamity .
i)
ii)
iii)
iv)
Why did the two brothers considered the school
+children to be in danger ?
Why they thought the children could escape the natural calamity inside their school building
constructed from metal sheets?
List the qualities exhibited by Kshitij and Dhruva.
5 Marks based questions-------Q1- A parallel plate capacitor is to be designed with a voltage rating 1 KV using a material of dielectric constant
3 and dielectric strength about 107 V/m . For safety we would like to field never exceed say, 10% of the
designed strength. What minimum area of the plates is require to have a capacitance of 50F.
Q2- The two plates of a parallel plate capacitor are 4mm apart. A slab of dielectric constant 3 and thickness
3mm is introduced between the plates with its faces parallel to them. The distance between the plates is so
adjusted that the capacitance of the capacitor becomes 2/3 of its original value. What is the new distance
between the plates?