TUTORIAL PHY150/Z S Mahmud/JUNE-OCT2015

CHAPTER 6: MAGNETISM

1. A proton moves with a speed of 1.0 x 105 ms

-1 through the Earth’s magnetic field. When

the proton moves eastward, it experiences a maximum magnetic force of 8.8 x 10-19

N.

What is the magnetic strength of the Earth’s magnetic field at that location? (Ans : 5.5 x

10-5

T)

2. An electron travels at an angle of 40º with the direction of a magnetic field of 0.40 T in

the –y direction. The speed of the electron us 3.00 x 106 ms

-1. Calculate the magnitude of

the magnetic force on the electron and the acceleration experiences by the proton.

3. A proton moves parallel to a magnetic field of 0.10 T with a speed of 2.0 x 106 ms

-1. Find

the magnitude of the acceleration of the proton.

4. A He2+

ion travels at right angles to a magnetic field of 0.80 T with a velocity of 105 m/s.

Find the magnitude of the magnetic force on the ion. (Ans : 2.56 x 10-14

N)

5. An electron is moving with a speed of 5 x 107 ms

-1 to a magnetic field of 0.5 T. (a) What

is the magnetic force on the electron? (b) What is the radius of the circle in which the

electron moves? (Ans : 4 x 10-12

N, 0.57 mm)

6. (a) What is the force on a charged carbon ion moving with a speed of 3 x 105 ms

-1 to a

magnetic field of 0.75 T. (Ans : 3.6 x 10-14

N)

(b) What is the centripetal acceleration of the ion? (Ans : 1.81 x 1012

ms-2

)

(c) What is the radius of the circle in which the ion moves? (Ans : 49.7 mm)

7. Calculate the force on a straight wire 11 cm long carrying a current of 12 A when the

wire is in a 200 μT magnetic field perpendicular to the wire. (Ans : 260 μN)

8. Find the force on each segment of the wire shown in Figure below, if B = 0.15 T. Assume

that the current in the wire is 5A.

9. A wire bearing a current of 10 A lies perpendicular to a uniform magnetic field, B. A

force on of 0.2 N is found to exist on a section of the wire 80 cm long. Determine the

magnetic field. (Ans: 0.025 T)

10. A coil of 20 turns has an area of 800 mm2 and bears a current of 0.5 A. It is placed with

its plane parallel to a magnetic field of intensity 0.3 T. Determine the torque on the coil.

(Ans : 2.4 x 10-3

Nm)

TUTORIAL PHY150/Z S Mahmud/JUNE-OCT2015

11. A rectangular loop 6 cm high and 2 cm wide is placed in a magnetic field of 0.02 T. If the

loop contains 200 turns and carries a current of 50 mA, what is the torque on it? Assume

that the face of the loop is parallel to the field. (Ans : 2.4 x 10-4

Nm)

12. A 3.0 μC charge is traveling with a speed of 5 x 104 m/s parallel to a very long and

straight wire. The wire is 8.0 cm from the charge and carries a current of 40.0 A in the

direction opposite to that the moving charge. Find the magnitude and direction of the

force on the charge.

13. Two parallel straight wires 20.0 cm apart carry currents in opposite direction. Current I1 =

3.0 A is out of page, and I2 = 7.0 A is into the page. Determine the magnitude and

direction of the magnitude field halfway between the two wires.

14. Two parallel straight wires 8.0 cm apart carry currents in same direction. Current I1 = 2.0

A and I2 = 4.0 A are into the page. Determine the magnitude and direction of the

magnitude field halfway between the two wires.

15. Two long and fixed parallel wires A and B are 13 cm apart and carry a current of 10 A

and 30 A respectively as shown below. Determine the magnitude and the direction of

magnetic field at point P.

16. Two long and fixed parallel wires A and B are 7 cm apart and carry a current of 20 A and

50 A respectively as shown below. Determine the magnitude and the direction of

magnetic field at point Z.

17. The two wires of a 5.0 m long appliance cord are 2.0 mm apart and carry a current of 5.0

A dc. Calculate the force one wire exerts on the other.

18. A solenoid 0.5 m long has 2000 turns. The magnetic induction near the center of the

solenoid is 0.08 T. What is the current in the solenoid? (Ans: 16 A)

19. Two long and fixed parallel wires, A and B, are 10 cm apart in air and carry currents of

40 and 20 A, respectively, in opposite directions. Determine the resultant magnetic field

(a) on a line midway between the wires andM parallel to them, (b) on a line 8 cm from

wire A and 18 cm from wire B. (Ans : 2.4 x 10-4

T, 7.8 x 10-5

T)

TUTORIAL PHY150/Z S Mahmud/JUNE-OCT2015

20. A solenoid has length L= 1.00 m and inner diameter d = 1.55 cm, and it carries a

current I = 4 A. It consists of five close-packed layers, each with 7 turns along length L.

What is B at its center?