1P January 2015 Flashcards
Sound waves are?
Longitudinal.
How does convection cause air movement?
The air is warmed, air expands and becomes less dense. Less dense air rises, cooler air displaces warmer air. Air cools and falls. Process of convection is repeated.
How should a student find an accurate value for the resistance of a piece of wire at a constant temperature?
Instrument to measure temperature, use a water to maintain constant temperature, use V=IR, repeat and find an average, use linear part of graph, use of gradient.
How to find refractive index using a glass box?
Use a ray box and protractor, vary angle of incident to obtain a range of values, n= sin i sine r. Plot a graph of sin i against sin r.
How is terminal velocity reached?
Weight acts downwards, drag acts upwards. Forces are balanced so acceleration = 0. Therefore constant velocity = no acceleration.
When a magnet is passed through a coil, why does a data logger record a varying voltage?
Voltage is induced because field in coil is changing. Current changes when magnet does. Changing amplitude due to decrease in amplitude.
Why does the voltage vary?
Speed of magnet changes, direction of magnet changes,
