2) Answers without relevant diagram/figure/circuit wherever necessary will not carry any marks. 3) Direct answers to Numerical problems without detailed solutions will not carry any marks. PART A I Answer ALL of the following questions. 10 × 1 = 10 1. A cube encloses a charge of 1 C. What is the electric flux through the surface of the cube? 2. The color code of a carbon resistor is Brown-Red-Brown-Gold. What is its resistance? 3. State Ampere’s circuital law. 4. Define magnetic permeability. 5. Name the law which gives the polarity of induced emf. 6. What type of a wave front is observed from a distant source of light? 7. Give an example for nuclear fusion reaction. 8. Define energy band gap in solids. 9. The output of OR gate is connected to the input of NOT gate. Name the equivalent logic gate. 10. What is the signal bandwidth offered by a coaxial cable? PART – B II Answer any FIVE of the following questions. 5 × 2=10 11. State Coulomb’s law in electrostatics and explain it in the case of free space. 12. How does the resistivity of the following materials vary with the increase in their temperature (i) metallic conductor and (ii) semiconductor?
Page 24 of 35 13. Mention the principle behind the working of a transformer. Can a transformer be used to step up a dc voltage? 14. Mention two characteristics of electromagnetic waves. 15. Using Huygens principle, draw a diagram to show the refraction of plane wave front incident obliquely on a surface separating two media. 16. Mention two observations of Geiger- Marsden's experiment on scattering of alpha particle. 17. Two nuclei have mass numbers in the ratio 8 : 125 . Calculate the ratio of their nuclear radii. 18. Explain the terms ‘range’ and ‘band-width’, used in electronic communication systems. PART – C III Answer any FIVE of the following questions. 5 × 3=15 19. Obtain the expression for capacitance of a parallel plate capacitor without dielectric medium between the plates . 20. Write the expression for the force acting on a charge moving in a uniform magnetic field. Mention the nature of a trajectory of the charged particle which is moving (i) parallel and (ii) perpendicular to the magnetic field. 21. Mention three distinguishing properties of diamagnetic and ferromagnetic materials. 22. Write the expression for time period of oscillation of small compass needle in a uniform magnetic field and explain the terms. In this case if the magnitude of the magnetic field is reduced to 1/4th, how does the time period change? 23. Derive the relation f = R/2 in the case of a concave mirror. 24. State Bohr’s postulates of hydrogen atom. 25. Obtain the expression for the half-life of a radioactive element.
Page 25 of 35 26. Name the device ‘D’ which is used as a voltage regulator in the given circuit. Rewrite the circuit by replacing the device ‘D’ with proper circuit symbol.
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- Winter '20