Physics chapter 6, section 1
If you rub a balloon against your hair, the balloon will attract your hair. We say the balloon is
electrically charged or static as a result of being rubbed. You can notice that an object is static in
various ways:
- The object attracts other objects (Hair and balloon)
- Sparks may jump across to other objects, you can hear/see this
A charged object usually loses its charge fast. The more water vapor is in the air, the faster the object
discharges.
There are two different kinds of charge. Objects that have the same charge
repel each other, and objects that have different charges attract each other. One
type of charge is called positive. The other one is called negative.
An uncharged object has the same amount of positive and negative electrons.
We than say the object is neutral. If you rub an object with a cloth, small
negative particles will jump across. These particles are called electrons. Only negative electrons
move, so you always make the negative electrons jump across.
In the figure on the right you can see that at number one, balls A and B are
not equally charged. One has more positive electrons, and the other has
more negative electrons. In such a case, we say that there is a voltage
difference. When you make a connection out of a conductor, electrons start
to move, and create an electrical current. This current only flows for a short
while, it will stop as soon as there is no more voltage difference between A
and B.
High voltages between charged objects and surroundings can make sparks
jump across, for instance a car. You can feel that when you get out of the
car, you feel a slight shock as the car discharges through your body.
If you want current to flow for a longer period of time, a voltage source is
needed.
You also have machines that can give an object a substantial electrical
charge. These machines are called electrifying machines or static electricity
generators. These can generate high voltages.
A small static electricity machine
Physics chapter 6, section 2
The resistance indicates the relationship of voltage and ampere inside a wire. When a wire has a high
resistance, it’s difficult for current to flow through, but when it has a low resistance, it’s fairly easy
to flow through. The resistance is equal to the voltage divided by the current.
𝑼
R=
𝑰
The U is given in Volts and the I is given in Ampere. R is in Ohms (Ω).
If you rub a balloon against your hair, the balloon will attract your hair. We say the balloon is
electrically charged or static as a result of being rubbed. You can notice that an object is static in
various ways:
- The object attracts other objects (Hair and balloon)
- Sparks may jump across to other objects, you can hear/see this
A charged object usually loses its charge fast. The more water vapor is in the air, the faster the object
discharges.
There are two different kinds of charge. Objects that have the same charge
repel each other, and objects that have different charges attract each other. One
type of charge is called positive. The other one is called negative.
An uncharged object has the same amount of positive and negative electrons.
We than say the object is neutral. If you rub an object with a cloth, small
negative particles will jump across. These particles are called electrons. Only negative electrons
move, so you always make the negative electrons jump across.
In the figure on the right you can see that at number one, balls A and B are
not equally charged. One has more positive electrons, and the other has
more negative electrons. In such a case, we say that there is a voltage
difference. When you make a connection out of a conductor, electrons start
to move, and create an electrical current. This current only flows for a short
while, it will stop as soon as there is no more voltage difference between A
and B.
High voltages between charged objects and surroundings can make sparks
jump across, for instance a car. You can feel that when you get out of the
car, you feel a slight shock as the car discharges through your body.
If you want current to flow for a longer period of time, a voltage source is
needed.
You also have machines that can give an object a substantial electrical
charge. These machines are called electrifying machines or static electricity
generators. These can generate high voltages.
A small static electricity machine
Physics chapter 6, section 2
The resistance indicates the relationship of voltage and ampere inside a wire. When a wire has a high
resistance, it’s difficult for current to flow through, but when it has a low resistance, it’s fairly easy
to flow through. The resistance is equal to the voltage divided by the current.
𝑼
R=
𝑰
The U is given in Volts and the I is given in Ampere. R is in Ohms (Ω).
