Physics Exam Questions Wrong Flashcards
What type of wave are wifi signals
Microwaves or radio waves
Can electromagnetic waves travel in a vaccum or not and explain why
They can
Because they are transverse waves
And so do not need particles to carry energy, unlike longitudinal waves
The formula linking speed, frequency and wavelength
Speed= frequency x wavelength
A black and dull surface hits the sun
And then a white and shiny surface nuts the sun,
Compare and Explain in terms of ideas about thermal energy transfer what happens to the temperature of each surface when they hit the sun and when they turn away from it
Black surface when hitting the sun:
black materials are better absorbers of radiation than white
So temperature increases faster than that if white object
But when facing away black,
Black materials are also better emitters or radiation than white,
So temperature decreases faster than white
What is parrallex error and how can you avoid it
-when the readings look dofferent at different angles,
Thus,
Measure it at eye level
Name three things to do in a hooks law experiment to make the results more reliable
1)read from eye level to avoid parrallex error
2)repeat and TAKE AN AVERAGE
3)make sure to read from the same point on the spring
State what axis extension is and what axis force is for hooks law
Extension is on x axis
Force is on y axis
When temperature decreases explain what happens to pressure
Particles lose kinetic energy so move less fast
So less frequent collisions per SECOND against the walls
so less force exerted per unit area
So pressure decreases
For Fleming left hand rule, state which finger represents what
Thumb= force
Index=magnetic field
Middle= current
Does light change speed when it is totally internally reflected
No
(Only changes speed when it’s refracted)
Give a condition for total internal reflection to occur
Must be from more dense to less dense medium
Is every ray that enters a light box, totally internally reflected?
No, only the angles that enter at an angle
(Eg Angles that enter at the normal do not reflect or refract and continue straight, because although they change speed, they don’t change direction.
Explain what happens in terms of speed and direction when waves enter a more dense medium from a less dense medium at the normal
Their speed decreases but direction does not change, thus they are not refracted
Explain what happens to waves when they enter a more dense medium from a less dense medium at the normal in terms of speed and direction
The speed decreases, but the direction does not, because they are entering at the normal.
Therefore the waves are not refracted
Equation to find the critical angle:
Sin C = 1/n(refractive index)
