29. Sources of Magnetic Field

Which of the following factors directly determines the strength of the magnetic field produced by a moving point charge at a given location in space?

Where do magnetic field lines exit the Earth today?

The amount of current determines the $\mathrm{magnitude}$ of the magnetic field when current flows through a conductor. Which property of the magnetic field is directly affected by the current?

Which of the following best explains what causes an object to be magnetic?

Which of the following statements correctly describes the direction of the magnetic field lines around a bar magnet?

When a compass is used near Earth's magnetic north pole, which pole of the compass magnet is attracted to Earth's magnetic north pole?

As you move a compass around a wire carrying current, what happens to the compass needle?

The current in a wire varies with time according to the relationship $I = 55 A - (0.65 A/s^2)t^2$ . What constant current would transport the same charge in the same time interval?

The current in a wire varies with time according to the relationship $I=55A-\left(0.65A/s^2\right)t^2$ . How many coulombs of charge pass a cross section of the wire in the time interval between $t=0$ and $t=8.0\text{ s}$?

The total amount of charge in coulombs that has entered a wire at time t is given by the expression Q=4t−t², where t is in seconds and t≥0. Find an expression for the current in the wire at time .

The total amount of charge in coulombs that has entered a wire at time t is given by the expression Q=4t−t², where t is in seconds and t≥0. Graph I versus t for the interval 0≤t≤4 s.