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  Work, Energy and Power Class 11 Notes Physics Chapter 6 Work, Energy and Power Class 11 Notes Physics Chapter 6 • Work is said to be done when a force applied on the body displaces the body through a certain distance in the direction of applied force. It is measured by the product of the force and the distance moved in the direction of the force, i.e., W = F-S • If an object undergoes a displacement ‘S’ along a straight line while acted on a force F that makes an angle 0 with S as shown. The work done W by the agent is the product of the component of force in the direction of displacement and the magnitude of displacement. • If we plot a graph between force applied and the displacement, then work done can be obtained by finding the area under the F-s graph. • If a spring is stretched or compressed by a small distance from its unstretched configuration, the spring will exert a force on the block given by F = -kx, where x is compression or elongation in spring, k is a constant call...

  Structure of Atom Class 11 Notes Chemistry Chapter 2 Structure of Atom Class 11 Notes Chemistry Chapter 2 • Discovery of Electron—Discharge Tube Experiment In 1879, William Crooks studied the conduction of electricity through gases at low pressure. He performed the experiment in a discharge tube which is a cylindrical hard glass tube about 60 cm in length. It is sealed at both the ends and fitted with two metal electrodes as shown in Fig. 2.1. The electrical discharge through the gases could be observed only at very low pressures and at very high voltages. The pressure of different gases could be adjusted by evacuation. When sufficiently high voltage is applied across the electrodes, current starts flowing through a stream of particles moving in the tube from the negative electrode (cathode) to the positive electrode (anode). These were called cathode rays or cathode ray particles. • Properties of Cathode Rays (i) Cathode rays travel in straight line. (ii) Cathode rays start from...

  Some Basic Concepts of Chemistry Class 11 Notes Chapter 1 • Importance of Chemistry Chemistry has a direct impact on our life and has wide range of applications in different fields. These are given below: (A) In Agriculture and Food: (i) It has provided chemical fertilizers such as urea, calcium phosphate, sodium nitrate, ammonium phosphate etc. (ii) It has helped to protect the crops from insects and harmful bacteria, by the use ‘ of certain effective insecticides, fungicides and pesticides. (iii) The use of preservatives has helped to preserve food products like jam, butter, squashes etc. for longer periods. (B) In Health and Sanitation: (i) It has provided mankind with a large number of life-saving drugs. Today, dysentery and pneumonia are curable due to discovery of sulpha drugs and penicillin life-saving drugs. Cisplatin and taxol have been found to be very effective for cancer therapy and AZT (Azidothymidine) is used for AIDS victims. (ii) Disinfectants such as phenol are u...