 |
| 1 | |
A straight wire 15 cm long, carrying a current of 6.0 A, is in a uniform field of 0.40 T. What is the force on the wire when it is (a) at right angles to the field and (b) at the 30° to the field? |
| | A) | (a) 36 N (b) 0.36 N |
| | B) | (a) 0.36 N (b) 0.18 N |
| | C) | (a) 2.25 N (b) 0.16 N |
| | D) | (a) 0 N (b) 0.72 N |
|
|
|
| 2 | |
An ion (q=+2e) enters a magnetic field of 1.2 Wb/m2 at a velocity of 2.5 x 105m/s perpendicular to the field. Determine the force on the ion. |
| | A) | 9.6 x 10-14 N |
| | B) | 6.0 x 105 N |
| | C) | 0 N |
| | D) | 6.7 x 10-14 N |
|
|
|
| 3 | |
An electron is accelerated from rest through a potential difference of 3750 V. It enters a region where B=4.0 x 10-3 T perpendicular to its velocity. Calculate the radius of the path it will follow. |
| | A) | 5.2 cm |
| | B) | 5.3 x 10-6 m |
| | C) | 1.8 x 108 m |
| | D) | 1.4 x 10-9 m |
|
|
|
| 4 | |
An electron is accelerated from rest through a potential difference of 800 V. It then moves perpendicularily to a magnetic field of 30 G. Find the radius of its orbit and its orbital frequency. |
| | A) | (a) 3.0 x 10-6 m, (b) 1.2 x 10-8 Hz |
| | B) | (a) 2.9 x 10-7 m, (b) 0.84 Hz |
| | C) | (a) 3.2 cm, (b) 84 MHz |
| | D) | (a) 3.2 x 107 cm, (b) 12.7 x 10-15 Hz |
|
|
|
| 5 | |
Two long parallel wires are 4 cm apart and carry currents of 2 A and 6 A in the same direction. Compute the force between the wires per meter of wire length. |
| | A) | 6.0 x 10-7 N/m, attraction |
| | B) | 6.0 x 10-5 N/m, attraction |
| | C) | 2.5 x 10-6 N/m, attraction |
| | D) | 6.0 x 10-5 N/m, repulsion |
|
|
|
| 6 | |
Two long fixed parallel wires, A and B, are 10 cm apart in air and carry 40 A and 20 A respectively, in opposite directions. Determine the resultant field (a) on a line midway between the wires and parallel to them and (b) on a line 8.0 cm from wire A and 18 cm from wire B (c) What is the force per meter on a third long wire, midway between A and B and in their plane, when it carries a current of 5.0 A in the same direction as the current in A. |
| | A) | (a) 8.0 x 10-4 T (b) 17.8 x 10-5 T (c) 1.2 x 10-3 N/m, toward B |
| | B) | (a) 2.4 x 10-4 T (b) 7.8 x 10-5 T (c) 1.2 x 10-3 N/m, toward A |
| | C) | (a) 2.4 x 10-6 T (b) 7.8 x 10-7 T (c) 0 |
| | D) | (a) 1.2 x 10-4 T (b) 6.0 x 10-6 T (c) 2.1 x 104 N/m, toward A |
|
|
|
| 7 | |
An ideal solenoid 50 cm long has 4000 loops wound on it. Compute B in its interior when a current of 0.25 A exists in the winding. |
| | A) | 10.0 mT |
| | B) | 2.5 mT |
| | C) | 2.5 x 10-5 T |
| | D) | 0.63 mT |
|
|
|
| 8 | |
A certain electromagnet consists of a solenoid (5.0 cm long with 200 loops) wound on a soft-iron core that intensifies the field 130 times. (We say that the relative permeability of the iron is 130.) Find B within the iron when the current in the solenoid is 0.30 A. |
| | A) | 4.9 x 10-4 T |
| | B) | 0.20 T |
| | C) | 2.0 mT |
| | D) | 1.2 x 10-5 T |
|
|
|
| 9 | |
An electron is traveling horizontally east in Earth's magnetic field. What is the direction of the magnetic force on the particle? |
| | A) | Up |
| | B) | Down |
| | C) | West |
| | D) | Zero |
|
|
|
| 10 | |
We desire to measure the current through and the voltage across a resistor connected in a circuit. How should an ammeter and a voltmeter be connected to the resistor? |
| | A) | Both are connected in parallel with the resistor. |
| | B) | Both are connected in series with the resistor. |
| | C) | The ammeter is connected in series and the voltmeter is connected in parallel with the resistor. |
| | D) | The ammeter is connected in parallel and the voltmeter is connected in series with the resistor. |
|
|
.