cycle test 1 questions Flashcards
describe three other differences between sound waves and light waves
1) sound is longitudinal, light is transverse
2) sound vibrations are in the direction of travel, light vibrations are perpendicular to the direction of travel
3) light is electromagnetic sound is not
4) light can travel through a vaccum, sound cannot
what is meant by the term electric current
the rate of flow of charge
explain the term critical anagle
the angle of incidence for when the angle of refraction is 90 degrees
explain how the spacecraft reacehd a low terminal velocity after opening its parachute
1) air resistance increases when parachute is opened
2) air resistance is greater than weight
3) resultant force is upwards
4) as speed decreases, air resistance decreases
the temperature and pressure of the treapped gas increase when its warmed
explain, in terms of particles, why the pressure of the trapped gas increases
1) particles have more energy in their kinetic store
2) more frequent collisions with the walls of the tube
3) each collision with the wall is harder
4) increasing the force on the walls of the container
explain why the amount of electriccal energy transferred to the motor is greater than the amount of gpe gained by the mass
1) energy transferred to surroundings as heat
2) mass also has ke
3) mass of strings has been ignored
describe the conditions needed for total internal reflection to occur
1) angle of incidence greater than critical angle
2) light travels from a more to less optically dense medium
describe how the teacher could measure the count rate from a radioactive source and correct the count rate for background radiation
1) use a gm tube
2) remove radioactive source
3) measure background radiation
4) several times to find an average
5) subtract background count from readings
explain why temperatures of the hot water and the cold water change
you should refer to different types of thermal energy transfer in your answer
1) hot water loses energy
2) cold water gains energy
3) thermal energy is transferred from hot to cold water by conduction until an equilibrium intermediate temperature is reached
4) heat energy loss occurs to surroundings in the form of convection and radiation
the hair dryer contains a coil of wire which is used to heat air passing through the hair dryer
explain why the coil of wire heats up when there is a current in it
1) coil has resistance in it
2) electrons lose energy
3) electron collision with ions in the coil
explain how a fuse protects a domestic appliance
1) excessive current
2) melts the fuse
3) breaking the circuit
the air near the bar receives energy by heating
explain how a convection current is formed in the air near the bar
1) temp of air increases
2) air expands
3) density of air decreases
4) warm air rises
5) cool air replaces warmed air
6) process repeats
explain why the plastic cover reduces how much water cools down at night
1) plastic keeps the hot air trapped within one space
2) air is a poor conductor
3) conduction is reduced
4) convection is reduced
explain how the design of the cup keeps the drink hot
1) the cup slows down energy transfer to surroundings
2) vaccum contains no particles
3) stopping conduction thrpugh the sides
4) air is trapped by the lid
5) reducting convection
6) shiny surfaces is a poor absorber of infrared
explain this change in frequency when the car is moving towards the radar speed gun
1) frequency increases
2) due to the doppler effect
3) car behaeves as the source of reflected waves
4) reflected wavefronts close together
5) reflected wavelenghts decreased
6) speed of waves is constant