1.Why it is not possible to have 100 % efficienct in a machine.
2.What is critical angle.How it is related to refractove index.
3.State 2 conditions where the work done by a force is zero.
4.State the energy change in loud speaker and photosynthesis. 5.what are 2 essential conditions for total internal reflection.
(Please help me friends )
Answers
1.it is not possible to have a machine hundred percent efficient because some part of its energy is lost in overcoming the friction and it is lossed in different forms of energy as sound, heat etc.
2.critical angle is the angle of incidence for which a ray of light passing through this angle from a denser medium to a rarer medium is totally reflected, means no refraction.
3.the work done by a force is zero when
(a) the displacement is zero
(b) the force acting is making an angle 90
4.in loud speaker the energy changes from electrical energy to sound energy. and in photosynthesis light energy to chemical energy.
5.(a) the light should pass from denser medium to rarer medium.
(b) the angle of incidence is greater than the critical angle.
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