Professor G. S. Mehmi

Faraday gave two laws on electromagnetic induction. Faraday's Ist Law : This law states that whenever magnetic flux (magnetic lines of force) linked with any closed circuit (loop) changes, an induced e.m.f. and hence, induced current is produced in the circuit which lasts so long as the flux changes. The direction of induced curret is such that it is inverse when flux increases and direct when flux decreases. Faraday's 2nd Law : The magnitude of induced e.m.f. produced in a circuit (coil) directly proportional to the rate of is change of magnetic flux linked with the circuit. If flux d ∮ changes in time dt, then rate of change of magnetic flux becomes  d ∮/dt. According to Faraday's 2nd law,  E ∝   d ∮/dt    ...(1) Applying constant of proportionality, then equation (1) becomes, E = - 1 d ∮/dt   ...(2) where -1 is constant of proportionality and - ve sign is represent the opposing nature of induced e.m.f. and induced current. If coil has N tur...

The construction of a ruby laser is shown in fig1. It consists of a pink rod, which is a crystal of aluminum oxide doped with 50% chromium oxide and 4 cm in length. Its ends are optically flat and one is fully and other is partly silvered. A coiled flash tube (Xenon lamp) surrounds the rod. When flash of light takes place, green and yellow light is absorbed by chromium ions and thus they are excited to higher energy states while the red is allowed to pass through. This red light suffers successive reflections at the silvered ends. Excited atoms jump to a common metastable state giving energy to the crystal. Energy in metastable state is equal to the energy of red light which is already present. Thus, the ions return to the ground state with the stimulated emission of red radiations. Since large number of chromium atoms are present in metastable state, thus stimulated emission is continuously amplified and hence an intense coherent beam of light leaked out into air through partly silver...

Short answer questions: Q1. Define reflection of light.  State and explain its laws. Q2. Define refraction of light. State and explain its laws. Also dine refractive index? Q3. Explain power of a lens. Give its relation and units. Q4.Give the application of TIR. Q5. Define electric lines of force.  Explain its properties. Q6. What is a capacitor.  Define capacitance and give its relation and units. Q7. Describe the factors of parallel plate capacitor on which the capacitance of a capacitor depends upon. Q8. Difference between AC and DC. Q9.Difference between E.m.f and potential difference. Q10. State Ohm's law with diagram and relation and units. And give experimental verification of Ohm's law. Q11. Find the equivalent resistance when three resistances are connected in series and parallel. Q12. Define a magnetic line of force.  Explain its properties. Q13. State and explain Faraday laws of electromagnetic induction. Q14. Explain Spontaneous emission,...

Short answer questions : Q1.  It is easier to pull than to push a lawn roller. Why? Q2.  What is difference between scalar and vector quantities ? Q3. What is difference between heat and temperature ? Q4. State triangle Law and parallelogram Law of Forces with diagrams. Q5. Define Young's modulus(Y) and bulk modulus(K)  and modulus of rigidity of elasticity (n). Give mathematical expression of it and S.I. units. Q6. Small drops of mercury are spherical. Explain why ? Q7. Define viscosity, coefficient of viscosity? Write their relation and units? Q8. State and explain Stoke's law. Q9. What is Power? Give its relation with work, also write the S.I. and CGS units of Power. Q10. Friction is necessary evil. Explain why? Q11. Explain the laws of friction? Q12. State and prove principle of Homogeneity of Dimensions with example. Q13. Explain stress Strain Curve.  Q14. Explain the modes of  transfer of heat.  Long answer questions : Q1. What do you m...

Chapter : Force And Motion Chapter : Work , Power And Energy Chapter : Units And Dimensions 

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