Electricity Flashcards
(19 cards)
Static electricity
A stationary electric charge typically produced by friction, which causes sparks or cracklings or the attraction of dust or hair
Examples of static electricity
Rubbing a pen on a jumper to make a stream of water move and the Van de Graaff generator to make hair stick up
Negatively charged
The objects gain electrons
Positively charged
Objects lose electricity
Like charges
Repel each other
Opposite charges
Attracted to each other
Insulator
Charge doesn’t travel through e.g. plastic
Conductor
Charge can travel through e.g. metal
Polythene rod
Gains electrons if a woollen cloth is rubbed on it (becomes negatively charged)
Perspex rod
Loses electrons if it is rubbed by a woollen cloth (becomes positively charged)
Earthing
Occurs when a charged object loses its charge to the earth through a conductor
Electric current
Caused by the flow of electrons through a good conductor such as a metal
Good insulator
Does not allow electric currents to flow
Conversion of electrical energy
Light - so we can see in the dark, Heat - so we can cook and heat buildings, Kinetic - for electrical motors, Sound - for music
Potential difference
The difference in electrical pressure between the positive and negative ends. Whenever there is a potential difference electricity will flow. This potential difference is known as Voltage and is measured in volts
Resistance
The opposition to the flow of electrons. The unit is Ohm and it is measured using an Ohmeter. If a resister is placed in an electric circuit, it will slow down the flow of electrons
Use of resistors
As the electrons push to get through the resistor the electrical energy is changed to heat energy. When resistors such as light bulbs
Ohm’s Law
Ohm’s Law states that voltage is directly proportional to current.
Bulbs in Series
The same amount of current flows through each bulb in the series. The voltage is split up, depending on the size of the bulb.
