1P Jan 2013 Flashcards
Advantage of sending signals through optical fibres?
Less prone to noise.
Method for finding resistance in different pieces of wire.
Connect wire to circuit. Read ammeter, read voltmeter. Measure length of wire with ruler. Repeat in different places along wire, take readings with different lengths.
Why might a precise scale give the wrong reading?
Parallax error.
What kind of energy is in wires?
Electrical.
How does fission lead to a chain reaction?
Nucleus splits, releasing neutrons which hit different U-235 nuclei.
Why are radio waves suitable for communications?
Can travel long distances.
Describe how a loudspeaker uses an electrical supply to produce sound waves.
Current in coil, alternating current, produces magnetic field, which interacts with field of permanent magnet, force on coil, vibrations in cone making longitudinal waves.
Why is gravitational field strength smaller on the moon than the earth?
Moon has a smaller mass.
Why does a feather fall to the ground slower than a hammer?
Feather has less mass, reaches terminal velocity before hammer as smaller drag force needed, so average velocity of feather is lower.
How is pressure caused inside a can?
Particles have kinetic energy and move in random directions colliding with walls, causing a force on the walls, Pressure is a force on an area.
