An object with negative charge is placed in a region of space where th

1.An object with negative charge is placed in a region of space where the electric field is directed vertically upward. What is the direction of the electric force exerted on this charge? A: It is up. B: It is down. C: There is no force. D: The force can be in any direction.

2.A particle with electric charge is fired into a region of space where the electric field is zero. It moves in a straight line. Can you conclude that the magnetic field in that region is zero?( )选项： A:Yes, you can. B:No; the field might be perpendicular to the particle’s velocity. C:No; the field might be parallel to the particle’s velocity. D:No; the particle might need to have charge of the opposite sign to have a force exerted on it. E:No; an observation of an object with electric charge gives no information about a magnetic field.

3.A particle with electric
charge is fired into a region of space where the electric
field is zero. It moves in a straight line. Can you conclude that the
magnetic field in that region is zero?() 选项： A、Yes,
you can. B、No;
the field might be perpendicular to the particle’s velocity. C、No;
the field might be parallel to the particle’s velocity. D、No;
the particle might need to have charge of the opposite sign
to have a force exerted on it. E、No;
an observation of an object with electric
charge gives no information about a magnetic
field.

4.A charged particle moves through a region of space that has both a uniform electric field and a uniform magnetic field. In order for the particle to move through this region at a constant velocity,选项： A: the electric and magnetic fields must point in the same direction.; B:the electric and magnetic fields must point in opposite directions.; C:the electric and magnetic fields must point in perpendicular directions.; D:The answer depends on the sign of the particle’s electric charge.

5.In a certain region of space, the electric field is uniform. It can be proved that the volume charge density in the region must be zero based on the Gauss's law.选项： A:正确; B:错误

6.What will be the direction of the drift velocity of electrons change with respect to the electric field? 选项： A、same as that of electric field B、opposite to that of electric field C、perpendicular to that of the electric field in a positive direction D、perpendicular to that of the electric field in a negative direction

7.If the electric field does positive work on a negative charge as the charge undergoes a displacement from point A to point B within an electric field, then the electrical potential energy ( )选项： A:electric fields cannot do work. B:decreases. C:increases. D:is positive. E:is negative.

8.When a charged particle moves through a magnetic field, the direction of the magnetic force on the particle at a certain point is选项： A:in the direction of the magnetic field at that point.; B:opposite to the direction of the magnetic field at that point.; C:perpendicular to the magnetic field at that point.; D:none of the above; E:The answer depends on the sign of the particle’s electric charge.

9.A uniform electric field of magnitude V/m is directed in the positive x direction. A +12.0μC charge moves from the origin to the point (x, y) = (20.0 cm, 50.0 cm). What is the change in the potential energy of the charge–field system? 选项： A、6.00´10^-4J B、-6.00´10^-4J C、3.00´10^-4J D、0

10.(2016.24)

A proton moves with constant non-zero velocity in a region of space that has a uniform magnetic field directed into the plane of the page. The proton moves directly up the plane of the page. What is the direction of the electric field in this region of space? Ignore gravity.

选项： A:

To the left

B:

To the right

C:

Down the plane of the page

D:

Up the plane of the page

E:

There is no electric field necessary

11.For the sources of electric and magnetic fields, which of the following statements is incorrect?选项： A:Any time-varying magnetic field gives rise to an electric field.; B:Any time-varying electric field gives rise to a magnetic field.; C:Any current gives rise to a magnetic field.; D:Any charge gives rise to a magnetic field.

12.About Gauss's law, which of the following statements is TRUE?选项： A:If the electric flux through a closed surface is zero, there must be no charge inside the closed surface.; B:If there is no charge inside the surface, the electric field inside the surface is zero.; C:If the electric field inside the closed surface is uniform, there is no charge inside the closed surface.; D:If there is no net charge inside the surface, the electric field over the enclosed surface must be zero.