1. Physics 1143,
Principles of Physics II
Recitation III

2. 2
A proton is released such that it has an initial velocity of 4.0 × 105 𝑚
𝑠
from left
to right across the page. A magnetic field of 1.2 T is present at an angle of 30º
to the horizontal direction. What is the magnitude of the force experienced by
proton? (𝑞𝑝 = 1.6 × 10−19 C)

3. A current-carrying wire of length 50 cm is positioned perpendicular to a
uniform magnetic field. If the current is 10.0 A and it is determined that there is
a resultant force of 3.0 N on the wire due to the interaction of the current and
field, what is the magnetic field strength?
3

4. A current of 20 A in a long straight wire produces a magnetic field of 42 μT at a
certain distance from the wire. Find this distance.

5. A proton, which moves perpendicular to a magnetic field of 1.2 T in a circular
path of radius 0.08 m, has what speed? (𝑞𝑝 = 1.6 × 10−19 C and 𝑚𝑝 = 1.67 ×
10−27 𝑘𝑔)

6. Superconductors can carry very large currents with no resistance. If a
superconducting wire is formed into a solenoid of length 50.0 cm with 500
turns, what is the magnetic field inside the solenoid when the current is 104 A?

7. 7
The two wires of a 2.0-m-long appliance cord are 3.0 mm apart and carry a
current of 8.0 A. Calculate the force between these wires.

8. A loop of area 0.25 m2 is in a uniform 0.02 T magnetic field. If the flux through
the loop is 3.83 × 10-3 T.m2, what angle does the normal to the plane of the loop
make with the direction of the magnetic field?

9. A planar loop consisting of four turns of wire, each of which encloses 200 cm2,
is oriented perpendicularly to a magnetic field that increases uniformly in
magnetic from 10 mT to 25 mT in a time of 5 ms. What is the resulting current
in the coil if the resistance of the coil is 5.0 Ω?

10. 10
A generator is designed to produce a maximum emf of 170 V while rotating
with an angular speed of 3600 rpm. Each coil of the generator has an area of
0.016 m2. If the magnetic field used in the generator has a magnitude of 0.050 T,
how many turns of wire are needed?

11. A simple AC generator consists of an N=10 turn coil of area A= 1200cm2 which
rotates at a constant frequency of f = 60 Hz in a B= 0.4T magnetic field. What is
the peak emf of the device?