incorrect exam questions Flashcards
why does a magnet fall more slowly in a copper tube?
- force on magnet
- force opposes the motion OR force on magnet due to magnetic field caused by current in tube
why very high temp needed to force two H nuclei together?
- high temperature produces high energy
- the molecules repel eachother
- both are postively charged/have like charges
What happens to the light after it passes the lens
- is focused
- travels toward a point
- diverges or spreads out from that point
how energy from the sun to be warming roads
- radiation
- light/infrared
- travel through space
- absorbed by road
cool wind how
- density decreases and air rises
- air is replaced by cool air
evaporatop
- higher speed molecules escape
- adverage kinetic energy of the molecules decreases
- temeprature is related to speed
why metals can conduct electricity
atoms vibrate and hit the delocalied electrons
electrons travel through the metal and hit atoms
transferring heat
how to use a stop watch to determine the time period of the pendulum
- use stop watch to time oscillations
- use of fiduciary aid to detemine a complete cycle
- use of multiple oscillations and division
How a gas exerts a pressure:
- moving particles hit walls
- momentum changes when particles hit walls
- force exerted by particles due to rate of change of momentum
- P = F/A
How does thermal energy transfer to worker whos of a distance to the metal
- By radiation
- EM waves, like infrared, travel to the worker
- are absorbed by the worker
why would magnet move left if north to north?
force is in the direction of the field
specific latent heat of fusion
energy transferred when 1kg of a substance freezes or melts
why mixture of ice and water remain at a lower temp after 10 mins than mixture of water
energy is needed for change of state so temperature doesn’t rise until this has taken place
mixture of ice and water will remain at 0 until all ice has melted
Explain, in terms of molecules, how the evaporation of sweat cools the person.
- in evaporation more energetic molecules escape
- lower energy molecules remian so remaining liquid is cooler
- thermal energy is taken from person to liquid
how does wind increase evaporation?
wind blows fast moving molecules away OR ensure molecules do not re-enter the liquid
if wider gap, what happens to waves in diffraction?
waves will pass through gap, remaining straight
as less diffraction occurs
EMF definition
energy supplied to drive a unit charge round a complete circuit
safety precautions which hospital staff taken when workiing with y-ray sources
- store in lead lined boxes
- limit expsoure time
- stand behind wall
- don’t let pregnant staff to work
Iodine-131 emits γ-radiation. It has a half-life of 8 hours.
Explain why this emission and this half-life make iodine-131 a suitable material for a tracer in medical diagnosis.
- y can be detected outside the body
- long enough half life to be detected
- short enough half life to soon have very little activity
- weakly ionising or pass out of body without harm
kWh
energy transferre in one hour at the rate of transfer of 1kW
Explain, in terms of forces and distances between particles, why the gas occupies a much greater volume than it does as a liquid.
Forces between particles are much greater in liquids than gases
Particles in gases are further apart
) We can see light from the Sun but we cannot hear any sound from it. WHY
sound needs a medium to travel through
light doesnt need a medium to travel through
voltage
work done in passing a charge through a component
EMF formula
W/Q = E
work done/charge = emf
