Test Papers

Electrostatics : A Practice Test Paper – 1

Time: 45 min

Max. Marks: 25

1. How does the force between two point charges change, if the dielectric constant of the medium in which they are kept, increases? [1]
2. Name the experiment which established the quantum nature of electric charge. [1]
3. Ordinary rubber is an insulator, but the special tyres of aircrafts are made slightly conducting. Why is this necessary? [1]
4. Draw electric field lines around an electric dipole. [1]
5. What would be the work done if a point charge +q is taken from  a point A to B on the circumference of a circle with another point charge +q at the centre? [1]
6. Obtain an expression for the potential energy of two charges q1 and q2 separated by distance r in a electric field E. [2]
7. Define electric field intensity. What is its SI unit? What is the relation between electric field and force on the charge? [2]
8. Obtain an expression for the electric potential at a point due to an electric dipole. [3]
9. Sketch equipotential surfaces for (i) a positive point charge (ii) Two equal positive point charges separated by a small distance (iii) a uniform electric field. [3]
10. (a) State Gauss Law (b) Using it derive an expression for the electric field intensity at a point near a thin infinite plain sheet of charge. (c) A point charge of 2 microcoulomb is at the centre of a cubic Gaussian surface 9cm edge. What is the net electric flux through all the surfaces of the cube? [5]
11. (a) Define electric dipole moment. (b) Derive expression for electric field intensity of a dipole at a point on its axial line. (c) Two charges +10μ C and – 10 μ C are placed 5 mm apart. Determine the electric field at a point P 15 cm away from its centre O on a line passing through O and normal axis of the dipole. [5]

Numericals from Kinematics

PHYSICS TEST (CLASS XI) Kinematics

1. A particle is projected at 60º to the horizontal with a kinetic energy K. What is the kinetic energy at the highest point
2. Which of the following statements is false for a particle moving in a circle with a constant angular speed?
   (a) the velocity vector is tangent to the circle
   (b) the acceleration vector is tangent to the circle
   (c) the acceleration vector points to the centre of the circle
   (d) the velocity and acceleration vectors are perpendicular to each other
3. A car is moving in a circular horizontal track of radius 10.0 m with a constant speed of 10.0m/s.A plumb bomb is suspended from the roof of the car by a light rigid rod of length1.00m. What is the angle made by the rod with the track is (g= 10 m/s²)
4. The distance traveled by an object along the axes are given by x=2t², y = t² – 4, z = 3 t – 5. What is the initial velocity of the particle
5. A boy playing o the roof of 10m high building throws a ball with a speed of 10 m/s at an angle of 30º the horizontal. How far from the throwing point will the ball be at the height of 10m from the ground?
6. If a body travels half of its path in the last second of its fall from rest; find the time and height of its fall?
7. An object A is kept fixed at the point x = 3m and y=1.25m on a moving along the +x direction with an acceleration 1.5 m/s. At the same instant a stone hitting the object during its downward motion at an angle pf 45º to the horizontal .all the motions are in X-Y plane .Find u and time after which stone hits the object. Take g = 10m/s²
8. Three particles a, b and c are situated at the vertices of an equilateral triangle ABC of side d at t=0. Each of the particles moves with constant speed v. A always has its velocity along BC and C along CA. At what time will the particles meet each other?
9. A man standing on road has to hold his umbrella at 30º with the vertical to keep the rain away he throws the umbrella and starts running at 10 km/h. he finds that  raindrops with respect to [a]the road, [b] the moving man.

10. A man can swim at speed of 3 km/h in still water. He wants to cross a 500 m wide river flowing at 2 km/h. he keeps himself always at an angle of 120º with the river flow while swimming. (a) Find the time he takes to cross river. (b) At what point on the opposite bank will he arrive?

11. A staircase contains three steps each 10cm high and 20 cm wide what should be the minimum horizontal velocity of a ball rolling off  the uppermost plane so as to hit directly the lowest plane?

12. A person is standing on a truck moving with a constant velocity of 14.7 m/s on a horizontal road .The man throws a ball in such a way that it returns to the truck after the truck has moved 58.8 m .find speed and the angle of projections
(a) as seen from the truck, (b) as seen from the road

13. An airplane has to go from a point A to another point B, 500 km away due 30º east of
north. a wind is blowing due north at a speed of 20 m/s (a) find the direction in which the pilot should head the plane to reach the time taken by the plane to go from A to B

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A Random Test from Magnetism

Each question carries one mark

• What is a magnetic dipole?
• What is the difference between electric field lines and magnetic field lines?
• Write an expression for the magnetic field at a point on the axis of a circular group carrying current and hence write equation for the magnetic dipole moment of the loop?
• What is Bohr magneton and write its equation and value?
• State Gauss’s law in magnetism?
• Define magnetic meridian?
• Define magnetic declination?
• Define angle of dip or magnetic inclination?
• Define magnetizing force and intensity of magnetization?
• Draw the hysteresis loop for a ferromagnetic substance.
• Define retentivity and coercivity
• Repulsion the surest test of polarity. Comment
• State Curie’s law of magnetism
• Define magnetic susceptibility
• Compare the relative permeability of paramagnetic , diamagnetic and ferromagnetic substances.

ELECTROSTATICS TEST PAPER FOR CLASS XII

1. What orientation of an electric dipole in a uniform electric field corresponds to its stable equilibrium?

2. What is the area of the plates of a parallel plate capacitor of capacitance 2F and with separation between plates 0.5 cm?

3. What is the work done in carrying a point charge 10 nC between two points separated by a distance 5 cm on an equipotential surface?

4. A parallel plate capacitor is made by stacking ‘n’ equally spaced plates connected alternatively. If the capacitance between any two plates is ‘C’, determine the resultant capacitance of the combination

5. Calculate the coulomb force between two a particles separated by a distance of 3.2 x 10^-15 m

6. Draw graph showing variation of electric field with distance for a uniformly charged metallic sphere.

7. An electron and proton are free to move in an electric field. Which one will have greater acceleration? Why?

8. Sketch two equipotential surfaces for (a) a point charge. (b) between two plane sheets of charge.

9. Show that the work done in rotating an electric dipole of dipole moment p in a uniform electric field E by an angle θ from the equilibrium postition W = PE(1-cos θ)

10. The given graph shows the variation of charge ‘q’ verses potential difference for two capacitors C1 and C2 .The capacitors have same plate separation, but the plate area of C2 is double that of C1.Identify the line in the graph corresponding to C1 & C2 and why?

11. Derive an expression for the torque acting on an electric dipole placed in a uniform electric field.

12. Derive an expression for the capacitance of a parallel plate capacitor.

13. You are given three capacitors of value 2μF, 3μF, 6μF. How will you connect them to a resultant capacity of 4μF?

14. Two equally charged identical metal spheres A and B repel each other with a force of 2·0 x 10^-5 N. Another identical uncharged sphere C is touched to A and then placed at the mid point between A and B. What is the net force on C?

15. A dielectric slab of thickness t introduced between the plates of a parallel plate capacitor separated by a distance d. (t < d). Derive an expression for the capacitance of the capacitor

16. Describe the principle construction and working of a Van de graff Generator with the help of a neat labeled diagram.

17. Use Gauss theorem to derive an expression for the electric field at a point due to

a. an infinite plane sheet of charge of uniform charge density σ

b. a thin infinitely long straight line  of charge of uniform charge density λ

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