9J — Force Fields and Electromagnets Flashcards
1) What are the parts of an atom?
2) What is the charge of an atom?
1) Protons, electrons and neutrons
2) It has no charge
1) What is static electricity?
2) What is an electric field?
1) A positive or negative charge on an insulating material caused when rubbing transfers electrons from one material to another.
2) An electric field is the space around a charged object which attracts and repels other charged objects.
1) What is resistance?
2) What does the resistance of a wire depend on?
1) Resistance is a way of saying how difficult it is for electricity to flow through something
2) The resistance of a wire depends on:
● the material from which it is made
● its length (longer wires have higher resistances)
● its thickness (thicker wires have lower resistances)
1) What is the unit for measuring resistance?
2) What is the formula for voltage?
3) How do you calculate resistance?
1) Resistance is measured in ohms.
2) Voltage = current × resistance
3) resistance = voltage / current
1) What type of magnet is a bar magnet?
2) What is an electromagnet?
1) A bar magnet is a permanent magnet, because it is always magnetic.
2) An electromagnet is a coil of wire with an electric current flowing through it. It is only magnetic while the current is flowing.
How can you make an electromagnet stronger?
You can make an electromagnet stronger by:
● Increasing the number of coils of wire
● Increasing the size of the current (by increasing the voltage)
● Using an iron core
1) What is the motor effect?
2) How does an electric motor work?
1) The force produced when a wire carrying a current is placed in a magnetic field.
2) A machine consisting of a coil of wire in a magnetic field. The coil spins when a current flows through it.
How can the speed of the motor be increased?
The speed of the motor (or the force it provides) can be increased by:
● increasing the size of the current
● increasing the strength of the magnetic field
● increasing the number of turns of wire on the coil.
