general Flashcards
describe energy stores and transfers of a falling object?
energy in object’s GPE store is mechanically transferred to its kinetic store.
what is dissipated energy?
energy has been transferred to the surroundings and cannot easily be used for a specific purpose.
Dissipated energy is a form of wasted energy.
when does thermal conduction occur (heat transfer)
more energetic atoms or ions vibrate faster and collide with neighbouring atoms or ions, transferring energy throughout the structure of the solid.
why does thermal conduction generally occur faster in metals than non-metals?
Thermal conduction occurs faster in metals because metals have free (delocalised) electrons, which speed up the energy transfer throughout the substance.
what controls brightness of a lmap- voltage or current?
what is shared in parallel circuit and what is same?
in parallel voltage is same- it allows circuit to get voltage from ains supply directly which is around 230 volts
current is shared/split
what is shared in series circuit and what is same?
current .
PD/ voltage is shared
what are 3 advantages of using parallel circuit for lighting?
- independant switching for rooms
- one bulb blowing will not affect other lamps
- each room can have diff intensities
- the lamps are usually brighter than in series circuit
- they all get same voltage and mains
does a higher refractive index mean more or less bending?
more, slows down more as it is more dense
There are several appliances in a kitchen including a toaster, a kettle, clothes iron, microwave oven and dishwasher.
discuss three hazards of using electricity in this kitchen.
- water conducts electricity, so can be dangerous if it comes in contact with a plug or socket.
- electrical devices with heating elements reach high temperatures which can cause insulation to melt and cause burns
- appliances damaged can be harm- leaky microwave radiation can cause cancer, and exposed live parts can cause shocks.
how is earth wire necessary for safety?
it is connected to the metal casing of appliance
so if live wire touches metal casing the earth wire will offer a low resistance path to Earth.
large current in earth
fuse will break/melt
circuit will break
in motor effect, how to make coil spin slower?
- use weaker magnetic field
-reduce current
-reduce voltage
-increase resistance in circuit
describe how the resistence of an LDR varies as light intensity changes
- bright light=low resistence
- inverse relationship
- bright at lower resistence
the acceleration of a car changes but driving force stays the same.
what could be two possible explanations?
- car going uphill
-air resistence increases
is heating energy store or transfer?
transfer
what are the 9 stores of energy?
- magnetic
- chemical
- thermal
- electrostatic
- nuclear
- kinetic
- GPE
- KPE
- EPE (Elastic potential energy)
the manly king gives every new child exciting chocolates
what are the 4 transfers of energy?
My elephant has rhythm
mechanical
electrical
heating (conduction,convection or radiation)
radiation (light and sound waves)
