paper 1 standard answers Flashcards
(9 cards)
Newton’s Third Law
when ‘object a’ exerts a force on ‘object b’, ‘object b’ exerts an equal and opposite force on ‘object a’
the force from ‘B’ is greated than the ‘resistive forces’ on ‘A’
therefore there is a resultant force
this causes an acceleration (N2)
The force from ‘B’ is greater than the ‘resistive forces’ on ‘A’, resulting in acceleration.
I/V Graphs - Filament Lamp
as voltage increases, current increases
the charge carriers collide with lattice ions
transferring some of their energy to the lattice ions
causing the ions to vibrate with greater amplitude
thus increasing temperature of the filament
and increasing collision rate with the charge carriers
reduces the increase of current with voltage (reference to graph)
This reduces the increase of current with voltage.
I/V Graphs - Thermistor
as voltage increases, current increases
the charge carriers collide with lattice ions
transferring some of their energy to the lattice ions
causing the ions to vibrate with greater amplitude
thus increasing temperature of the thermistor
and causing electrons to move from the valence band to the conduction band
which increases charge carrier density (n)
which increases current and therefore decreases resistance
LDR/Thermistor Response to Environmental Changes
as light intensity/temp of the surroundings increases
energy is transferred to electrons in the valence band
causing them to move into the conduction band
thus increases charge carrier density (n)
thus increasing current and decreasing resistance
Electromagnetic Induction
when the ‘coil’ moves relative to the ‘magnet’ (or vv)
there is a change in flux linkage with the ‘coil’
induces an EMF across it
which produces a current through it
magnitude of the EMF induced is equal to the rate of the change of flux linkage
direction of emf/current is such that it opposes the change causing it
The direction of EMF/current opposes the change causing it.
Transformer/Linked Coils
alternating current in the primary coil causes an alternating magnetic field around it
this is transmitted through the core
there is changing flux linkage with the secondary coil
which induces an alternating EMF across the secondary coil
thus an alternating current is produced if there is a complete circuit
magnitude of EMF determined by Faraday’s law
tehrefore the EMF induced is proportional to number of turns
The EMF induced is proportional to the number of turns.
Cyclotron
alternating PD between the dees which produces alternating electric field
accelerates the ‘protons’ between the dees
there is a magnetic field inside the dees, perpendicular to their plane
this causes the ‘proton’ to follow a curved path
as the velocity of the ‘protons’ increases, the radius of their path inside the dees increases
so the time a ‘proton’ spends inside each dee is CONSTANT
and the frequency of the pd between the dees is constant
The frequency of the PD is constant, and the time spent in each dee is constant.
Linac
composed of a set of metal drift tubes in a line with an electric field between them
the ‘electrons’ are accelerated in the gaps between the tubes
by the electric field / potential difference
each adjacent tube has opposite polarity
electric field is alternating so that as an ‘electron’ emerges from one tube, the next tube is ‘positive’
time spent in each tube mush be the same (for an alternating field)
as the ‘electrons’ move faster, tube get longer
Each adjacent tube has opposite polarity, and tubes get longer as electrons move faster.
Gold Foil Alpha Scattering
atom is mostly empty space: most of the alpha particles passed through without deflection
the positive charge is concentrated in the nucleus at the centre: some of the alpha particles are deflected by angles less than 90 - repelled by positive nucleus
the mass of the atom is concentrated at the centre: very few alpha particles are delfected by angles greater than 90 - large momentum change
Positive charge is concentrated in the nucleus, causing some alpha particles to be deflected by angles less than 90.
