physics exam questions Flashcards
why does different refraction happen at a boundary between air and glass?
- different parts of the wavefront enter glass at different times
- and the velocity is less in glass
- so one part of the wave front changes speed before other parts
A student measured degrees of 6.0, 6.3, 6.4 and 5.8 from a 10 degree incidence angle - why should they have NOT recorded these results?
as the resolution of a protractor is 1 degree so it can’t be used to measure to 1dp
Transformer X is used to transform power station electricity into cables for mains electricity in the national grid - why and how does it do this?
It increases the p.d, therefore decreasing the current! this reduces thermal energy transfer (to the surroundings), increasing the efficiency of power transmission
Transformer Y is used to transform mains electricity in the national grid to peoples homes. why and how does it do this?
it decreases the potential difference to a safer value for homes
difference between alpha external and internal radiation?
external - is stopped by skin and low penetrating so not very damaging!!!
internal - absorbed by living tissues, is highly ionising so the contamination can lead to cell mutation and possibly cancer
