Exam 14: Magnets and Electromagnetism

Two particles move into a magnetic field. They enter moving at the same speed and direction. The magnitude of the charge on each is known to be the same. One particle curls to the right and the other to the left upon entering the field, the one on the left moving in a larger circle than the one on the right. From this we can say that

If an electron moves in a magnetic field,

A little magnetic compass has a needle whose tips are clearly labeled N and S. The compass is placed next to a single circular loop of wire lying flat on a wooden table. The current in the loop is clockwise. What happens?

Two identical coils of wire are placed on a single horizontal wooden broom handle. The coils are separated by a few centimeters. We now run identical currents in the same direction through each coil. The coils experience

Imagine a magnetic field pointing into the plane of this page. An electron moves across the paper from left to right. The direction of the magnetic force on the electron will be

When there is a changing magnetic flux through an electric circuit, the direction of the induced current in the circuit is determined by _____________ Law.

A magnetic compass points towards the north geographic pole of the Earth because

The scientist credited with discovering that electric currents produce magnetic fields was

A positively charged ping pong ball is sitting stationary on the floor in the center of a room. There is also a constant, uniform magnetic field in the room that points toward the ceiling. If I now start the ball rolling toward the back of the room, the resultant motion of the ball, as observed from the ceiling, will be

The south pole of a bar magnet is moved toward an aluminum ring, along the axis of the ring. As the magnet approaches, the changing magnetic flux induces an electric current in the ring that, when seen from the bar magnet, corresponds to positive charge carriers flowing

When a current is induced by a changing magnetic field B₁, the current always produces a second magnetic field B₂ such that

The south pole of a bar magnet is moved toward a short helical coil of wire (solenoid) along the axis of the coil. The coil has 100 turns and the ends of the coil are connected to form a closed circuit. If the coil is replaced with a single loop of the same type of wire, and the magnet is moved exactly as before, the current induced in the loop is

Bar A has one end painted green and the other end red and may or may not be a magnet. A student brings the north pole of a bar magnet M close to the green end of A. He observes that the green end is attracted. He can conclude that

Which of the following cannot induce a voltage in a loop of wire?

An ideal transformer is used to either increase or decrease the voltage in an AC circuit. When the output voltage is greater than the input voltage of a transformer then

A bar magnet and an electrically polarized object are placed next to each other on a table. What happens?

Two long bar magnets are aligned so that north poles face each other. The magnets are separated by 1 cm, and a repulsive force between the north poles is 0.04 N. When the separation is increased to 2 cm the force will be

A positive charge is released from rest near a bar magnet. The magnetic force on the charge

A loop of wire is oriented in the magnetic field as shown below (the plane of the loop is perpendicular to the direction of the magnetic field). Which of the following is true?

In outer space, you observe a straight stream of electrons flowing past you at 14.5 miles per second, about the same speed that Mars moves on its orbit around the sun. You maneuver your spacecraft to face the current so that the electrons are moving from left to right and so that you are 10 m from the stream. In what direction does a compass needle point?