The circuit of current induced in a coil due to its rotation in mf with ammeter and voltmeter 0
Answers
1. Three identical coils A, B and C are placed with their planes parallel to one another. Coils A and C
carry current as shown. Coil B and C are fixed. The coil A is moved towards B with uniform motion. Is
there any induced current in B?
2. Two coils are being moved out of magnetic field- one coil is moved rapidly and the other slowly. In which case is more work done and why?
3The figure shows two identical rectangular loops (1) and (2), placed on a table along with a straight line current carrying conductor between them.
(i) What will be the directions of the induced currents in the loops when they are pulled away from the conductor with same velocity?
(ii) Will the e.m.f. induced in the two loops be equal? Justify your answer.
4 Give the direction in which the induced current flows in the coil mounted on an insulating stand when a bar magnet is quickly moved along the axis of the coil from one side to the other as shown.
5. A bar magnet M is dropped so that it falls vertically through the coil C. The graph obtained for voltage produced across the coil vs time is shown in figure (b). (i) Explain the shape of the graph. (ii) Why is the negative peak longer than the positive peak?
6.A coil A is connected to a voltmeter V and the other coil B to an alternating current source D. If a large copper sheet C is placed between the two coils, how does the induced e.m.f. in the coil A change due to current in coil B?
7. A cylindrical bar magnet is kept along the axis of a circular coil, when the magnet is rotated (a) about its own axis, and (b) about an axis perpendicular to the length of the magnet, in which case the induced emf will be more?
8.How does the self inductance of an air core coil change, when (i) the number of turns in the coil is decreased, (ii) an iron rod is introduced in the coil? A copper coil L wound on a soft iron core and a lamp B are connected to a battery E through a tapping key K. When the key is suddenly opened, the lamp flashes for an instant to much greater brightness. Explain.
9. How is the mutual inductance of a pair of coils affected when separation between the coils is increased? The number of turns of each coil is increased? A thin iron sheet is placed between the two coils, other factors remaining the same? Explain your answer in each case.
10. A rectangular wire frame, shown below, is placed in a uniform magnetic field directed upward and normal to the plane of the paper. The part AB is connected to a spring. The spring is stretched and released when the wire AB has come to the position A’B’ (t = 0). How would the induced emf vary with time? Neglect damping.
11. Why does metallic piece become very hot when it is surrounded by coil carrying high frequency alternating current?
12. Three students X, Y, and Z performed an experiment for studying the variation of alternating current with angular frequency in a series LCR circuit and obtained the graphs as shown. They all used a.c sources of the same r.m.s. value and inductances of the same value. What can we (qualitatively) conclude about the (i) capacitance value (ii) resistance values Used by them? In which case will the quality factor be maximum? What can we conclude about nature of the impedance of the set up at frequency wo?
13.In the circuit shown below, R represents an electric bulb. If the frequency of the supply is doubled, how should the values of C and L be changed so that glow in the bulb remains unchanged?
14 An air cored coil L and a bulb B are connected in series to the mains as shows in the given figure: The bulb glows with some brightness. How would the glow of the bulb change if an iron rod is inserted in the coil? Give reasons in support of your answer
15. When a circuit element ‘X’ is connected across an a.c. source, a current of √2A flows through it and this current is in phase with the applied voltage. When another element ‘Y’ is connected across the same a.c. source, the same current flows in the circuit but it leads the voltage by π/2 radians.(i) Name the circuit elements X and Y. (ii) Find the current that flows in the circuit when the series combination of X and Y is connected across the same a.c. voltage.
16. Fig shows a light bulb (B) and iron cored inductor connected to a DC battery through a switch (S). (i) What will one observe when switch (S) is closed? (ii) How will the glow of the bulb change when the battery is replaced by an ac source of rms voltage equal to the voltage of DC battery? Justify your answer in each case