IB Physics 5.4 Test

At double the distance from a long current carrying wire, the strength of the magnetic field produced by the wire decreases to

1/2 of its original value.

What fundamental fact underlines the operation of essentially all electric motors?

A current-carrying conductor placed perpendicular to a magnetic field will experience a force

A horizontal wire carries a current straight toward you. From your point of view, the magnetic field caused by this current

Circles the wire in a counter-clockwise direction

According to Lenz's law the direction of an induced current in a conductor will be that which tends to produce which of the following effects?

Oppose the effect which produces it

Doubling the number of loops of wire in a coil produces what kind of change on the induced emf, assuming all other factors remain constant?

The induced emf is 4 times as much

A circular coil lies flat on a horizontal table. A bar magnet is held above its center with its north pole pointing down. The stationary magnet induces (when viewed from above)

no current in coil

The direction of the force on a current-carrying wire in a magnetic field is described by which of the following?

perpendicular to both the current and the magnetic field

A current carrying circular loop of wire lies flat on a table top. When viewed from above, the current moves around the loop in a counterclockwise sense. What is the direction of the magnetic field caused by this current, inside the loop? The magnetic field

points straight up

The South Pole of a magnet Points towards

the South pole

Two long parallel wires are placed side-by-side on a horizontal table. If the wires carry current in the same direction,

the wires attract each other

Two long parallel wires are placed side-by-side on a horizontal table. If the wires carry current in the opposite directions,

the wires repel each other

An electron has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. The direction of the magnetic field is

to the west.

A wire lying in the plane of the page carries a current toward the bottom of the page. What is the direction of the magnetic of the magnetic force it produces on an electron that is moving perpendicularly toward the wire

toward the bottom of the page

If a bar magnet is divided into two equal pieces,

two magnets result