Force fields and electromagnets Flashcards
What does an atom consist of ?
A central nucleus, small electrons and equal positive and negative charges.
Does and atom have a charge?
No they have no overall charge because negative and positive charges are equal.
What happens when insulating materials are rubbed together?
The object gains electrons and a negative charge. The other object has a positive charge.
What does a positively charged object attract?
Negative charged object
What will two objects with the same charge do when together?
Repel
What is the space around a charged object?
Electric field
What does arrows on a diagram show?
The direction a positive charge would move
What is resistance?
How easy or difficult it is for an electrical current to pass through a component
What does the size of the current depend on?
The resistance and the voltage
The higher the voltage…
The higher the current (if the resistance stays the same)
The higher the resistance…
The lower the current (if the voltage stays the same)
What does the resistance of a wire depend on?
The thickness (thicker wires have lower resistances), The length (longer wires have higher resistances), The material of which it is made from.
What are the units for measuring resistance?
OhmsΩ
How do you measure volts?
voltage = current × resistance
How do you measure resistance?
resistance= current/voltage
A bar magnet is a…
Permanent magnet, it is always magnetic and cannot be turned off. There are also two magnetic poles (north seeking and south seeking)
What does a wire with electric flowing through it have?
A magnetic field
What is an electromagnet ?
A wire coiled around that has an electric current running through it. It is only a magnet when electricity is running through it. The shape of the magnetic field is similar to a bar magnet.
How do you make an electromagnet stronger?
Having an iron core, increasing the number of coils, increasing the current (by increasing voltage). Although there is a limit to how much current can be passed through it safely.
What will happen when a wire carrying a current crosses a magnetic field?
The wire will experience a force called the motor effect
What does an electric motor consist of?
A coil of wire in a magnetic field
When there is a current in the coil of a motor what happens?
A force on each side of the coil makes it turn
How do you increase the speed of the motor?
Increasing the size of the current, increasing the strength of the magnetic field, increasing the turns of wire on the coil
What materials are magnetic?
Iron, nickel and cobalt (also steel is mostly iron so can be considered)
