Assignment Chapters 6 & 7

1. A straight conductor is 23 cm long and is immersed in a magnetic field of strength 1.34 T.

The angle the conductor makes to the field lines is 58^o. If the force on the wire is 3.76 N,

what is the current in the wire? (3 marks)

2. A battery cable in an automobile has a current of 18 A running in it. The earth's magnetic field

has a strength of 3.9 X 10^-5 T, and makes an angle of 66^o to the cable. If the force on the

cable is 4.8 X 10^-4 N, what is the length of the cable? (3 marks)

3. An electron of mass 9.11 X 10^-31 kg enters a magnetic field of strength 3.73 X 10^-2 T at an

angle of 75.0^o to the magnetic lines. The electron travels at a speed of 3.62 X 10⁶ m/s and

has a charge of -1.6 X 10^-19 C. What is the distance between the spirals of the path of the

electron? (5 marks)

4. A proton is traveling in a circular path of radius 3.60 X 10^-3 m in a magnetic field of strength

2.80 X 10^-2 T. The mass and charge of the proton are 1.6.7 X 10^-27 kg and +1.60 X 10^-19 C

respectively. Through what electric potential difference must this proton be accelerated to

produce this motion, if we assume the proton enters the magnetic field perpendicular to it?

(4 marks)

5. Three parallel wires running perpendicular to this page are carrying currents of 5.0 A, 8.0 A

and 12.0 A as indicated in the diagram.

By using the coordinate system shown, what is the magnetic field at the point labeled D?

(Remember to give the direction.) (7 marks)

6. A magnetic field of strength 3.7 X 10^-1 T is required to engage a starter in an automobile. The

current is 18.0 A. If the solenoid is 10.3 cm long, how many turns of wire are present?

(3 marks)

7. Two wires are 13 cm apart and carry currents of 4.7 A and 13.3 A in opposite directions. If

each wire is 2.3 m long, what is the force between the wires, and is it attractive or repulsive?

(3 marks)

8. A particle with charge 3.2 X 10^-19 C enters perpendicularly to a magnetic field of strength

3.7 X 10^-2 T. The radius of the path is 2.8 X 10^-2 m. If the period of revolution is

3.55 X 10^-6 s, what is the mass of the particle? (4 marks)

9. X-rays from an X-ray machine have a frequency of 3.2 X 10¹⁵ Hz. What is the wavelength of

the X-rays? (2 marks)

10.

For the diagram shown, if the magnet is moved in the direction of the arrow, what pole must B

be in order to induce the current shown? (1 mark)

11. An electrical transmission line has a power rating of 15.2 kW and a resistance of 0.93 W.

What must the electrical potential in the wire be for a power loss of 0.32%?

(3 marks)

12. Electrical energy must be supplied to an appliance with a resistance of 326 W at an electrical

potential of 3.6 X 10¹ V. The electrical potential in the incoming line is 370.0 V. The primary

coil of a transformer has 3000 turns on it.

a) How many turns must there be on the secondary coil? (2 marks)

b) What is the current in the primary coil? (2 marks)

January 19, 2014