C7 Flashcards
Energy is
Ability to do work
Forms of energy
Light, electrical, heat, potential, nuclear, sound, kinetic, chemical
Earth receives what from the Sun
Heat and light energy
Sources of energy
Sun, waves, water, wind, biomass, radioactive substances, geothermal, fossil fuel
Electrostatics
Electric charges that are stationary
What will happen when two different insulating materials such as glass and silk are rubbed against one another
When seperated, friction between the two objects will cause one of the objects to become positively charged while the other, negatively charged
Electroscope
Detect the existance of electric charges
Occurrence of lightning
When negative charges in the bottom of the cloud are attracted to the positive charges in the ground
How to reduce the electrostatic charges at the body of the tanker
Metal chain. Electrostatic chargers will flow from the body of the tanker to the ground through the metal chain, without producing any sparks
Electric current (I)
Rate of flow of electrons
Unit for electric current
Amphere(a)
Electric current is measured using
Ammeter
Voltage (v)
Energy needed to move electrons between to points
Unit for voltage (v)
Volt (V)
Voltage is measured using
Voltmeter
Resistance
The ability to resist electric current
Unit for resistance
Ohm
Electric current is made up of
Source of electrical energy, electrical components, connecting wire
Electrical components
Switch, dry cell, bulb, resistor, voltmeter, ammeter, galvanometer
Types of electric circuit
Series, parallel
SCA
Itotal = I1=I2
PCA
Itotal=I1+I2
SCV
Vtotal=V1+V2
PCV
Vtotal=V1=V2
SCR
Rtotal=R1+R2
PCR
1/Rtotal=1/R1+1/R2
Pros of series circuit
Same amount of electric charge, all electrical components are controlled by the same switch
Cons of series circuit
One bad, all bad.,
Pros of parallel circuit
All can be controlled separately, one bad will still be ok
For a room, which circuit is better. Why.
Parallel, can be controlled separately. One bad, all still ok
Electric magnet
Electric conductor
Electricmagnet eg
straight wire, a coiled wire or a solenoid
Electromagnet becomes a
temporary magnet when an electric current flows through the electric conductor
Strength of the magnetic field of an electromagnet
Amount of the electric current that flows
Advantage of an electromagnet
strength of its magnetic field can change according to the amount of the electric current that flows through the electromagnet.