SCIENCE 9 FINAL Flashcards
What is biomass?
Biomass- organic matter, such as food or agricultural waste, used as an energy source
What are the kinds of energy found in a D-Cell?
Chemical & Electrical
What is Ohm’s Law?
Ohm’s Law states that-
> The resistance of a conductor stays constant
> The current is directly proportional to the voltage applied
Electrolyte
A paste or liquid that conducts electricity because it contains chemicals that form ions
What is the difference between a Dry Cell and a Wet Cell?
A dry cell’s electrolyte is in form of a paste. They are generally sealed
A wet cell’s electrolyte is in liquid form (ex. Sulfuric Acid)
What is a cell?
Why isn’t a cell a battery?
A cell is a device capable of generating electrical energy from chemical reactions
A battery is a set of cells
What is electroplating?
Coating a metal with a thin layer of silver or gold
What is electrolysis?
Decomposition of a substance by an electric current (split into individual elements)
What is an electrical discharge?
Sudden transfer of electrical charge from one object to another, indicated by a spark
Electromagnet
Coil of insulated wire that becomes a magnet when current flows through it
Electrochemistry
The study of chemical reactions involving electricity
Why does lightning hit a tree before a golf club on the ground?
Lightning wants to take the quickest path to the ground
Why are lightning rods installed on to tall buildings?
Tall buildings are a natural target for lightning. Installing these rods causes the discharge to be conducted harmlessly to the ground
Superconductors
Conductors that have no resistance to electron flow. However these substances need to be at impractical temperatures for every day use
What is resistance measured in?
Ohms (Greek Letter Omega)
What is current measured in
Amperes (A)
What is power measured in?
Watts (w)
kilowatts (kW)
What is energy measured in?
Joules (J) Mega joules (MJ)
Kilowatt Hours (kW•h)
kW= W/1000
What is time measured in?
Seconds (s) for joules
Hours (h) for kilowatt hours
Why can’t a device be 100% efficient? (unless it is an electric heater!)
There will always be wasted energy (Mostly heat energy due to friction)
Why are electric engines more efficient than combustion engines?
Electric engines have less moving parts therefore less friction. This results into less wasted energy
What is geothermal energy?
It is the energy derived from the internal heat of Earth
What is a rheostat or variable resistor?
Resistor whose resistance can be changed by adjusting the portion of the resistor the current travels through
