1P June 2014 Flashcards
What two EM waves are used in cooking?
Microwave and infrared.
What is meant by energy is conserved?
Total energy always has the same value.
Describe the nature of a beta particle.
Electron.
How can scientists find the age of a rock?
There is a known proportion of when rocks form. Determine activity now. Compare activity now to original activity. Determine half-lives passed. Calculate age with reference to half lives.
How to find whether an object reaches terminal velocity.
Need a timer and ruler. Determine time for ball to pass between two points, determine the distance apart. Repeat lower down. Speed = distance / time.
How an earth wire acts as a safety feature?
Earth connected to metal casing, if casing becomes live provides low resistance path to earth, so large current in earth wire.
Why should objects be fitted with earth wires?
Objects have metal casing which conduct and can cause electric shocks.
Explain why a coil spins when switch is closed?
Current in coil creates magnetic field. Magnets interact with field, which creates a force on the wire.
Explain how Brownian motion provides evidence that air is made of small particles?
Smoke particles move with random motion and collide with smaller particles, which you cannot see.
Why would something travel further on the moon than on the earth?
Value of g lower, lack of air resistance on the moon.
Explain how nuclear fission can lead to a chain reaction?
Neutrons released, slowed by moderator, and are absorbed by other U-235 nuclei.
Why is shielding needed?
Reactor material is radioactive and radiation can cause ionisation of cells.
The resistance of the filament lamp changes as the voltage increased, explain these changes in resistance.
Lamp heats up, greater chance of electron collision, hence resistance increases.
