role of physics
...ite down four methods of reducing friction. (b) Define the following: i) Centre of Gravity ii) Displacement iii) Resultant Vector iv) Specific Heat v) Systematic Error vi) Elasticity (c) State Newton’s Law of Gravitation and derive the relation F=G m1 m2 r2 (d) An aero plane flying a velocity of 600km/H making an angle of 30o with the vertical direction. Find the velocity of its shadow on the ground if the sun is vertically above the plane. 3. (a) With the help of trigonometric rations find the magnitudes of horizontal and vertical components of a vector. (b) Define an Inclined Plane. Derive the formula for its Mechanical Advantage. (c) Write down the S.L. units of the following: i) Momentum ii) Temperature iii) Specific Heat iv) Stress v) Energy vi) Gravitational Constant (d) State PASCAL’s Principal and write down its three uses in daily life. OR Draw the figure of Hydraulic Press and write down its working with its one use. 4. (a) State Boyle’s Law and Charles’s Law and derive the general gas equation PV=nRT. (b) Define Torque. Write down the factors, which it depends. How is it measured? (c) An object of mass 100kg is raised 2m above the ground using an inclined plane of length 10m. Calculate the effort applied parallel to the inclined plane. (d) Write down the uses of bimetalic strip and with the help of a diagram explain its use in Fire Alarm. SECTION-B 5. (a) With the help of a diagram write down the construction and working of a parallel plate capacitor (b) State Columb’s Law and Joule’s Law. (c) Write down any two points of differences between each of the following: i) Concave Lens and convex Lens ii) Regular and Irregular Reflection of Light iii) Insulator and Conductor (d) Define and Electric Circuit and write down any three characteristics of resistance connected in parallel. 6. (a) draw a ray diagram of a Compound Microscope and write down its working. (b) Define the following: i) Radius of Curvatire of a Spherical Mirror ii) Unit of Charge iii) Magnetic Field iv) Angle of Minimum Deviation v) Polarization. (c) Write down the Newton’s Corpuscular Theory of Light or Wave Theory of Light. (d) An object is placed in front of a concave mirror at a distance of 30cm. If the radius of curvature of the mirror is 20cm, find the position and nature of the image. 7. (a) What is Galvanometer? How is it converted into an Ammeter and a Voltmeter? (b) Write down four characteristics of the image formed by a plane mirror. (c) An electric heater has a resistance of 20 Ohms and it work when a potential difference of 22 volts is applied across its terminals. Find the current passing through the heater and its power rating. (d) Find the focal length of a convex lens if P=5cm, q=10cm, and the image is virtual. SECTION-C 8. (a) Define the following: i) Wavelength ii) Time Period, iii) Radioactivity, iv) P-N Junction Diode. (b) Write down any two points of difference between each of the following: i) Fussing, ii) Forward-biased and Reverse-biased, iii) Musical sound and Noise (c) Write three merits of a transistor. (d) Write four properties each of Alpha, Beta and Gamma Rays. 9. (a) Define of the following: i) Radio, (ii) Periodic, iii) Longitudinal, iv) Nuclear Reactor (b) Write down any three precautions to minimize the danger of radiation. (c) Define the loudness of sound and write down three factors on which it depends IMPORTANT DIFFERENCES Scalar Vector 1. Those quantities, which do not require the mention of direction for their complete specification, are called scalar quantities. Quantities, which require the mention of direction for their complete specification, are called Vector quantities. 2. Scalars are represented by a magnitude, which is any number with a proper unit. Vectors are represented by a magnitude which is a number with proper unit and also direction. 3. Scalar quantities are added, subtracted and multiplied by ordinary algebra. Vector quantities are added and subtracted by vector algebra. 4. Some examples of scalar quantities are mass, speed, time, temperature, length and work etc. Some examples of vector quantities are force, weight, moment, momentum and velocity etc. g G 1. It is the acceleration due to gravity. It is universal gravitational constant. 2. Its value at the surface of earth is 9.8m/s2. Its value is 6.67 x 10-11Nm2/kg2 3. Its value is variable Its value is constant throughout the universe 4. It is determined by free fall method and simple pendulum Its value is determined by cavendish experiment. 5. It is a pulling force. It is not a pulling force. Kinetic Energy Potential Energy 1. K.E is the energy due to the motion of a body. P.E is the energy due to the position of the body. 2. Its value increases with velocity. Its value increases with height 3. Its value is equal to ½ the product of mass and square of velocity. K.E = ½ mv2 Its value is equal to the product of the weight mg and height h. P.E = mgh 4. It can be converted into P.E. It can be converted into K.E. Force Energy 1. Force is the agent that changes or tends to change the state of rest or motion of a body. Energyis the capability to do a work. 2. Its unit is Newton in S.I system. Its unit is joule in S.I system. 3. Total amount of force in the universe is not constant. Total amount of energy in the universe is constant. It can neither be created nor destroyed. However it can change form. Heat Temperature 1. Heat is the total amount of kinetic energy possessed by the molecules of a body. Temperature is the average amount of kinetic energy possessed by the molecules of a body. 2. Heat is measured in Joules, calories or Briti...