One reason why we know that magnetic fields are not the same as electric fields is because the force exerted on a charge +q
a. is in opposite directions in electric and magnetic fields.
b. is in the same direction in electric and magnetic fields.
c. is parallel to a magnetic field and perpendicular to an electric field.
d. is parallel to an electric field and perpendicular to a magnetic field.
e. is zero in both if the charge is not moving.
[Ques. 2] Equal charges, one at rest, the other having a velocity of 104 m/s, are released in a uniform magnetic field. Which charge has the largest force exerted on it by the magnetic field?
a. The charge that is at rest.
b. The charge that is moving, if its velocity is parallel to the magnetic field direction when it is released.
c. The charge that is moving if its velocity makes an angle of 45o with the direction of the magnetic field when it is released.
d. The charge that is moving if its velocity is perpendicular to the magnetic field direction when it is released.
e. All the charges above experience equal forces when released in the same magnetic field.
[Ques. 3] A velocity selector uses a fixed electric field of magnitude E and the magnetic field is varied to select particles of various energies. If a magnetic field of magnitude B is used to select a particle of a certain energy and mass, what magnitude of magnetic field is needed to select a particle of equal mass but twice the energy?
a. 0.50 B
b. 1.4 B
c. 2.0 B
d. 0.71 B
e. 1.7 B
[Ques. 4] What value of B should be used in a velocity selector to separate out 2.0-keV protons if E is fixed at 80 kV/m?
a. 0.18 T
b. 0.11 T
c. 0.15 T
d. 0.13 T
e. 0.23 T
[Ques. 5] What is the kinetic energy of an electron that passes undeviated through perpendicular electric and magnetic fields if E = 4.0 kV/m and B = 8.0 mT?
a. 0.65 eV
b. 0.71 eV
c. 0.84 eV
d. 0.54 eV
e. 1.4 eV
[Ques. 6] A proton is accelerated from rest through a potential difference of 2.5 kV and then moves perpendicularly through a uniform 0.60-T magnetic field. What is the radius of the resulting path?
a. 15 mm
b. 12 mm
c. 18 mm
d. 24 mm
e. 8.5 mm
[Ques. 7] A proton is accelerated from rest through a potential difference of 150 V. It then enters a region of uniform magnetic field and moves in a circular path (radius = 12 cm). What is the magnitude of the magnetic field in this region?
a. 18 mT
b. 12 mT
c. 15 mT
d. 22 mT
e. 10 mT
[Ques. 8] A proton with a kinetic energy of 0.20 keV follows a circular path in a region where the magnetic field is uniform and has a magnitude of 60 mT. What is the radius of this path?
a. 4.1 cm
b. 2.9 cm
c. 3.4 cm
d. 5.1 cm
e. 2.4 cm
[Ques. 9] An electron follows a circular path (radius = 15 cm) in a uniform magnetic field (magnitude = 3.0 G). What is the period of this motion?
a. 0.12 s
b. 1.2 ms
c. 0.18 s
d. 1.8 ms
e. 1.8 s
[Ques. 10] What is the radius of curvature of the path of a 3.0-keV proton in a perpendicular magnetic field of magnitude 0.80 T?
a. 9.9 mm
b. 1.1 cm
c. 1.3 cm
d. 1.4 cm
e. 7.6 mm
Quick Reply
