june 2018 Flashcards
(12 cards)
Explain why the study of seismic waves provides evidence for the structure of the earth’s core
because S waves cannot travel through a liquid
and S waves do not travel through the outer core
Why does the movement of the r bar magnet into the coil induce a potential difference across the coil?
The generator effect- magnetic field lines cut by coil
The further a swimmer dives below the surface of the sea, the greater the pressure on the swimmer
Increasing depth increases the volume of the water column above the swimmer
increasing the weight/force of water acting on the swimmer
The student concluded that for a plane mirror, the angle of incidence is equal to the angle of reflection. Do u agree?
within experimental
accuracy….
use of data hehe
State one change the student should make to the apparatus if he wants to use the same method to investigate diffuse reflection
Replace the mirror with an irregular reflecting surface like paper
Explain why the velocity of the satellite changes as it orbits the earth
gravity causes the satellite to accelerate forwards the earth
the acceleration causes a change in direction
velocity changes because direction changes
Why do scientists sometimes have different models like the wave and particle models of light
different models may be appropriate in different situations
Explain why scientists replace an old scientific model with a new model
New evidence
evidence cannot be explained using an existing model
new model explains new evidence
Explain refraction happens at the boundary between the deep water and shallower water
velocity is slower in shallow water
so edge of the wave entering the shallow water slows down
but the part of the wave in deeper continues at a higher speed leading to a change in direction of the wave fronts
Explain why the wave fronts do not refract at the boundary
Every point on the wave fronts enters the shallow water at the same time
so every point slows down at the same time
When there is a current in the coil, the coil rotates continuously in an electric motor. Explain why.
The sides of the coil experience a force in opposite directions
the force cause moment that act in the same direction
Each half turn the two halves of the rotating commutator swap from one brush to the other
keeping the forces in the same direction
