17 EMI Quiz ans

1 Name: …………………… Class: ………… Marks: ………./ 1 5 Time: 25 mins TUTORIAL 15: ELECTROMAGNETIC INDUCTION QUIZ 1 2 3 4 5 1 A metal bar lies as shown with its midpoint at the interface between two regions of uniform magnetic fields of opposite directions as shown. The magnitude of the magnetic field is the same in both regions. The bar moves in the indicated direction. Which point or points is/are at the highest potential? A Point A B Point B C Point C D Points A and C 2 When a coil is rotated in a magnetic field, the induced e.m.f. E varies with time as shown below. Which of the following graphs, drawn to the same scale, would be obtained if the speed of rotation of the coil is halved? A B C D E t E t t E E t E t x x x x x x x x x x x x A B C v

2 3 Two coils P and Q enter a magnetic field at the same time, as shown. P has the same length but twice the width of Q and is moving with half the speed of Q. Which of the following correctly shows the e.m.f. induced in the coils as they enter the field? A B C D e.m.f. time Q P e.m.f. time Q P e.m.f. time Q P time Q P e.m.f. Magnetic field P Q vP vQ

3 4 A circular coil with its plane horizontal is held firmly in a clamp and its terminals are connected to a data-logger. A bar magnet with its axis along the coil axis is released from rest from a position above the coil so that it drops through the coil, as shown below. The data-logger is used to measure the induced e.m.f. produced. Which graph shown below best represents the variation of the induced e.m.f. E with time? 5 A closed loop moves with an acceleration parallel to a long straight wire carrying a steady current as shown below. Which of the following statements is true? A The induced current in the loop will be clockwise. B The induced current in the loop will be anti-clockwise. C There will be no induced current in the loop. D The magnitude of the induced current in the loop will vary with the speed at which the loop moves.

4 Magnet Disc h 6 A conducting disc of mass m, within a vertical smooth cylinder, is released from height h above a strong magnet as shown in Fig. 6.1. (a) Using the laws of electromagnetic induction, explain the following observation as the disc falls along the cylinder. (i) The temperature of the disc increases. ……………………………………………………………………………………… ……………………………………………………………………………………… …………………………………………………………………………… ..…… [2] (ii) The acceleration of the disc is smaller than the acceleration of free fall. ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………… ..… [2] (b) The disc is replaced with a split ring as shown in Fig. 6 .2 and