CBSE Physics Electromagnetic Induction and Alternating Current Expected Questions : Unit VI
Short Answer Type Question
Q. 1. Show that the units of CR and L/R are the same as those of time.
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Q. 2. Explain on what factors does the induced e.m.f. in a coil rotating in uniform magnetic field depend.
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Q. 3. What are Faraday’s laws of electromagnetic induction ?
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Q. 4. Define coefficient of self induction. Give its unit.
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Q. 5. Explain the production of eddy currents in a conductor.
Q. 6. What is a transformer ? What is its principle ?
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Q. 7. Explain why there is sparking when an electrical circuit is ‘broken’ but not when it is ‘made’,
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Q. 8. In any a.c. circuit, is the applied instantaneous voltage equal to the algebraic sum of the instantaneous voltage across the series elements of the circuit, is the same true for rms voltage ?
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Q. 9. Explain : voltage across L and C in series are π (180°) out of phase, while for L and C in parallel, currents in L and C are π (180°) out of phase.
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Q. 10. For circuit used for transporting electric power, a low power factor implies large power loss in transmission.
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Q. 11. Power factor can often be improved by the use of capacitor of appropriate capacitance in the circuit.
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Q. 12. An applied voltage signal consists of superposition of a d.c. voltage and an ax. voltage of high frequency. The circuit consists of an inductor and a capacitor in series. Show that the d.c. signal will appear across capacitor C and a.c. signal across inductor L.
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Q. 13. A choke coil in series with a lamp is connected to a d.c. source. The lamp is seen to shine brightly. Inserting an iron core in choke causes no change in the lamp’s brightness. What will happen if connection is made to an a.c, source ?
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Q. 14. What is the significance of — ve value of instantaneous current ?
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Q. 15. Distinguish between resistance, resistor ; inductance, inductor ; capacitance, capacitor.
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Q. 16. Distinguish between resistance, inductive reactance, capacitive reactance and impedance.
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Q. 17. What are the dimensions of magnetic flux ? Is it possible that a current carrying wie does not tend to rotate in a magnetic field ?
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