Physic definitions (Electrostatics, magnets, electric current

what is vector and scolar?

directed / undirected quentities

2 examples of vectors and scalars

vectors

• force

• Velocity

Scalars

• volume

• Mass

Proparties of magnets

1. magnets have 2 poles

   • North and south→ opposite poles attract, like poles repel

2. Permanent magnets and ferromagnetic materials

   • Iron, cobalt, nickel always attract

3. If you break a magnet in half, each half still behaves as a complete magnet→ magnetic poles can not be separated.

What do magnetic materials contain on a microscopic level?

Magnetic domains

When is a material magnetized?

magnets and ferromagnetic materials contain magnetic domains. if the magnetic domains are aligned, the material is magnetized.

What is the difference between a soft magnetic material and a hard magnetic material?

soft

• easily magnetized

Hard:

• retain their magnetization

How can the magnetic domains be brought out of alignment?

When the magnet is dropped or heated.

Magnetic field

A magnetic field is the space, surrounding a magnet, where other magnets experience a force.

Definition of the direction of a magnetic field line?

The direction of the field shows the direction in which a magnetic North pole is pushed.

Elementary charge

The smallest unit of electric charge that is possible→ 1.602 times 10^-19

Electric field

The region surrounding a charge wehre forces act upon other charges.

Electric field strength

The electric field strength is measured by the force on a test charge, and it‘s proportional to the force divided by the size of the test charge.

Definition of the direction of an electric field line

The direction of the electric field vector corresponds to the force acting on the positive test charge.

Uniform field

A field in which the force on a test charge is equal at every point in the field (same magnitude, same direction)

Voltage

Work done on a test charge divided by the magnitude of the test charge.

Electric current

A means of transportation for electrical energy

what is the purpose of the electric current?

It is a means of transportation for energy.

what requirements need to be met for an electric current to flow?

There must be a voltage source and a closed conducting loop.

Series circuit

All lamps share the same conducting loop. If one lamps is unscrewed from the socket, all lamps will go out.

Parallel circuit

Each lamp has its own conducting loop and its own connection to the voltage source. If one lamp is unscrewed from the socket, only the unscrewed lamp will go out.

Direct current

electrons always move in the same direction. Positive pole stays positive and negative pole stays negative.

Alternating current

The electrons move back and forth. The poles switch between negative and positive.

Electrical resistance

Consumers and wires (resistors) slow the the current down. Resistance is the hindrance to the flow of charge.

What does the electrical resistance of a wire depend on?

Temperature, cross sectional area, length and material

What is the short circuit? What happens to the current if a short circuit occurs?

A short circuit is a direct connection between the poles of the voltage source. The absence of resistance leads to a very large circuit.

Here’s a graph showing how the electrical

resistance of three wires made of three

different materials 1, 2 and 3 relates to

temperature.

Describe in your own words how the electrical

resistance of three different materials 1, 2

and 3 changes, while the temperature

increases.

1: The resistance increases with increasing temperature

2: The resistance does not depend on the temperature

3: The resistance decreases with increasing temperatur