Class 11 Physics Important Questions

Physics Important Questions

Mechanics

1. State the parallelogram law of vector addition. Derive the expression for the magnitude and direction of the resultant of two vectors inclined at an angle θ from each other.
2. State triangle law of vector addition. Obtain an expression for the resultant of two vectors P and Q inclined at angle θ.
3. Define projectile. Show that the path of a projectile projected horizontally from the top of a tower is parabolic. At what angle does it hit on the ground?
4. A projectile is fired with a velocity v and making an angle θ with the horizontal. Derive expressions for:
   1. Maximum height
   2. Time of flight
   3. Horizontal range
   Also find the condition for maximum horizontal range.
5. State and prove the principle of conservation of linear momentum.
6. Derive Newton's first law and third law of motion from Newton's second law of motion.
7. What is the angle of repose? Show that when a body just begins to slide down on an inclined plane, the coefficient of friction is equal to the tangent of the angle of inclination of the plane.
8. Define work. Derive an expression to calculate work done by a variable force.
9. What is the principle of conservation of energy? Show that total mechanical energy of a body is conserved when it moves under the action of a gravitational field.
10. What is elastic collision? Prove that the colliding objects exchange their velocities in one-dimensional elastic collision.
11. Define centripetal force. Show that the acceleration of a body moving in a circular path of radius r with uniform speed v is v²/r and is directed towards the centre of the circle.
12. What is a conical pendulum? Show that the period of oscillation of this pendulum is given by T = 2π√(l cosθ / g) , where the symbols have their usual meanings.
13. What do you mean by the banking of a curved path? Derive an expression for the banking angle.
14. Derive an expression for the variation of acceleration due to gravity of the Earth with altitude and explain its meaning.
15. What is gravitational potential energy? Obtain an expression for the gravitational potential energy of a body at a distance r from the centre of the Earth.
16. Define escape velocity. Find an expression for the escape velocity from the surface of the Earth.
17. What do you mean by parking orbit? Derive an expression for the orbital velocity and hence find the time period of the satellite revolving around the Earth.
18. Explain the concept of a geostationary satellite. Find an expression for the total energy of the Moon revolving around the Earth.

Heat

1. Define linear and superficial expansivities of solids. Show that β = 2α, where the notation has its usual meaning.
2. Define coefficient of linear and cubical expansion of a solid and establish the relation between them.
3. Define linear and cubical expansivities of solids. Derive an expression for the variation in density of a solid when its temperature is raised from θ₁°C to θ₂°C.
4. Describe a method to determine the linear expansivity of a solid. Can the cubical expansivity be derived from this value?
5. Define the coefficient of real and apparent expansion of a liquid and derive the relation between them.
6. Distinguish between real and apparent expansion of a liquid. Describe, with mathematical detail, a method to determine real expansivity of a liquid.
7. Define thermal heat capacity of a substance. Describe the method of mixtures to determine the specific heat capacity of a solid.
8. State and explain Newton's law of cooling and derive the expression for the specific heat of the liquid by the method of cooling.
9. Define latent heat of fusion of ice. Describe the method for the measurement of it in the laboratory.
10. What is latent heat of vaporization of water? Develop an expression for the determination of the latent heat of vaporization of water.
11. Define Boyle's law and Charles' law. Prove PV = nRT.
12. On the basis of kinetic theory of gases, deduce the relation P = ⅓ρ¯c² , where the symbols have their usual meanings.
13. Starting from the relation P = ⅓ρ¯c² in kinetic theory of gases, derive Boyle's law, Charles' law and the ideal gas equation.
14. Define the coefficient of thermal conductivity. Describe Searle's method of determination of thermal conductivity of a good conductor.
15. What do you mean by a perfectly black body? State and explain Stefan's law of black body radiation.

Ray Optics

1. How will you differentiate between real and virtual images? Obtain an expression for the relation between object distance, image distance and the focal length in the case of a convex mirror.
2. Prove that 1/f = 1/u + 1/v for a concave mirror when the image formed is virtual/real, where u, v and f have their usual meanings.
3. What is lateral shift? Derive an expression for its value. How does the lateral shift change with the increase in the angle of incidence?
4. What do you mean by minimum deviation of light when passing through a prism? Show that the deviation produced by a small-angle prism is independent of the angle of incidence.
5. Show that μ = sin[(A + D_m)/2] / sin(A/2) for a prism, where the notations carry their usual meanings.
6. Derive the lens maker's formula and write the unit of the power of a lens.
7. Derive an expression for the combined focal length when two thin lenses are combined coaxially.
8. What is chromatic aberration? Show that for a lens, the chromatic aberration is the product of dispersive power and focal length of mean light.
9. Define achromatism and derive an expression for the condition of achromatic combination of two thin lenses in contact.

Electrostatics

1. What is electrostatic induction? How can you charge a given sphere positively by the method of induction?
2. What is electric potential? Derive the formula for the potential at a point due to a point charge.
3. State Gauss's theorem in electrostatics and use it to find the electric field intensity due to a hollow charged spherical conductor.
4. State and explain Gauss's law of electrostatics. Apply it to obtain an expression for the electric field of a linearly charged body.
5. State Gauss's law. Use it to find the electric field due to an infinite thin plane metallic sheet.
6. Define potential gradient. Derive a relation between electric field intensity and potential gradient.
7. Define electric potential. Derive an expression for the potential difference formula and hence obtain the potential at a point due to a point charge.
8. What do you mean by the term capacitance? Find the equivalent capacitance of two capacitors when they are connected:
   1. In series
   2. In parallel
9. Define capacitance of a capacitor. Deduce an expression for the capacitance of a parallel-plate capacitor.
10. What is a capacitor? Find an expression for the energy stored in a charged capacitor.