Conceptual Physics-Magnetism Unit-Test Flashcards
What is the basic cause of magnetism?
Moving Electrons and magnetic domains. Moving electrons case large groups of atoms to have all their North and South poles aligned. These are called magnetic domains. When all the domains in an object have the same orientation, it is magnetized.
What does the basic cause of magnetism explain?
Why, when a magnet is split, two new magnets with their own north and south poles are created, and how objects can become magnetized.
Is the Earth a magnet?
Yes
What is a compass?
A small device that uses a magnet to line up with the Earth’s north and south poles.
What is a magnetic field?
It is an area where the magnetic force is the strongest, but it is even stronger at the poles.
How is a magnetic field shaped?
Oval, arcs going from one pole to another
circular around a wire with current running through it.
What happens when current moves through a wire?
A magnetic field is created around it because the domains are aligned by the current.
What are the similarities and differences between a permanent magnet and an electromagnet?
They are similar because they both have north and south poles. They are different because only the electromagnet can switch poles, vary its strength, be turned off and on, and needs a source of electricity.
How does a galvanometer detect the presence of an electric current?
When a current runs through its coils a magnetic field is created which deflects the needle. It shows the direction of current by the direction the needle moves. It is a small magnet which is attracted to the field around the wires.
How can the strength of an electromagnet be increased?
You can add coils, increase the current, or increase the size of the core.
How does an electric current cause a motor to move?
Current goes through an electromagnet on the armature, which causes it to change poles when the commutator switches the current. The poles are attracted and repelled by the field magnets, and it moves in a circular motion.
How does a generator convert kinetic energy to electrical energy?
It turns wires within a larger magnetic field, taking kinetic/moving energy from wind or water or other sources.
How does the idea of conservation of energy relate to the operations of motors and generators?
No energy is lost, it is just converted from kinetic to electrical and vice versa. It does not create energy from nothing.
What causes a generator to produce an alternating current?
As the wire turns and cuts through the flux lines perpendicularly to the magnetic fields, it produces current first in one direction then the other.
What is the difference in the process of generating electricity by using coal compared to using wind energy?
Coal is burned to heat water which creates steam which turns a turbine. Wind directly turns and turbine and is renewable.
What is the difference between renewable and nonrenewable energy sources?
Renewable energy can be replaced within a lifetime, nonrenewable cannot. Renewable is also always available.
What are the principle parts of a motor?
The field magnets, armature, comutator and brushes
Define field magnets
two magnets which attract and repel the armature.
