Weak Flashcards
Conditions for total internal reflection
Light ray is travelling from a MORE optically dense medium to a LESS optically dense medium
Angle of incidence is greater than the critical angle
What happens to the current in a circuit if the total resistance of the circuit increases
Current will DECREASE
What quantity does not change when a light ray enters a glass block?
Frequency does not change. Wavelength changes and wavespeed changes but frequency does not change
Simply, what is Kirchoff’s first law
Total current entering junction= total current leaving junction
Simply, what is Kirchoff’s second law?
Sum of emf’s= sum of p.d’s
What is plane polarised light?
Oscillations are restricted to one plane of motion
Perpendicular to the direction of travel
How can you tell is light is unpolarised
Rotate a polarising filter in front of the light source
Intensity should not change
Reasons why a solar panel may not be 100% efficient
-Some energy converted to thermal energy
-Light may not be incident on the panel at 90 degrees
-Intensity of light may be lower due to clouds
Why can you not create a good interference pattern with two regular lamps
The light from the lamps is not monochromatic and not coherent
As it does not have a constant phase difference
Why are photoelectrons only released above a certain frequency?
1 photon interacts with 1 electron
Electrons absorb the energy from the photons
There is a minimum energy required for photoelectrons to be released
E=hf so there is a minimum frequency for photoelectrons to be released
What does intensity of light affect in photoelectric effect
Intensity only affects the number of photoelectrons released
Intensity does not affect the energy of the photoelectrons
How can you increase the accuracy of readings
Take repeats and taking a mean
One way of improving how you read oscillations of a pendulum
Using a fiducial marker
Why would a count rate not reach zero?
Because of background radiation which a data logger will pick up
What conditions are needed to measure g by dropping a ball bearing
Air resistance and upthrust should both be negligible
Equillibrium definition
Resultant force on an object is zero
Sum of moments about any point is zero
Find distance travelled on a velocity time graph
Area under graph
Feature of a free body diagram for an object in equilibrium
Resultant force is 0
Magnetic flux symbol and unit
Symbol is B and unit is T
Magnetic flux density symbol and unit
Symbol is phi and unit is Wb
What is weight actually
The reaction acting on us from the floor
Features of a radial field
Magnetic field lines get further apart
Direction of magnetic field lines
Higher to lower
100V to 0V
100V to -100V
Reasons why solar panels may not be suitable for large applications
-Not enough surface area
-Some measurements may be estimated to be too small
-More power may be needed at certain points
