Magnetic effect of current

Units of a magnetic field might be:

• C·m/s

• C·s/m

• C/kg

• kg/C·s

 An electron (charge = −1.6× $10^{-19}$  C) is moving at 3× $10^5$   m/s in the positive x direction. A magnetic field of 0.8T is in the positive z direction. The magnetic force on the electron is: 

•  4× $10^{-14}$   N, in the positive z direction 

• 4× $10^{-14}$  N, in the negative z direction 

•  4× $10^{-14}$  N, in the positive y direction

•  4× $10^{-14}$   N, in the negative y direction 

At any point the magnetic field lines are in the direction of:

• the magnetic force on a moving positive charge

• the magnetic force on a moving negative charge

• the velocity of a moving positive charge

• none of the above

The magnetic force on a charged particle is in the direction of its velocity if:

• it is moving in the direction of the field

• it is moving opposite to the direction of the field

• it is moving perpendicular to the field

• never

The direction of the magnetic field in a certain region of space is determined by firing a test charge into the region with its velocity in various directions in different trials. The field direction is:

• one of the directions of the velocity when the magnetic force is zero

• the direction of the velocity when the magnetic force is a maximum

• the direction of the magnetic force

• . perpendicular to the velocity when the magnetic force is zero

An electron is moving north in a region where the magnetic field is south. The magnetic force exerted on the electron is:

• zero

• up

• down

• east

A magnetic field CANNOT:

• exert a force on a charged particle

• change the velocity of a charged particle

• change the momentum of a charged particle

• change the kinetic energy of a charged particle

A hydrogen atom that has lost its electron is moving east in a region where the magnetic field is directed from south to north. It will be deflected:

• up

• down

• north

• south

A beam of electrons is sent horizontally down the axis of a tube to strike a fluorescent screen at the end of the tube. On the way, the electrons encounter a magnetic field directed vertically downward. The spot on the screen will therefore be deflected:

• upward

• downward

• to the right as seen from the electron source

• to the left as seen from the electron source

An electron travels due north through a vacuum in a region of uniform magnetic field B that is also directed due north. It will:

• be unaffected by the field

• speed up

• slow down

• follow a right-handed corkscrew path