Paper One: Electric and Magnetic Fields Flashcards
Define an electric field.
A region of space where a charged particle feels a force.
What is the equation for electric field strength relating charge and force?
E = F / Q , Electric field strength = force / charge.
What is the equation for the force on two charged particles?
F = ( Q1 x Q2 ) / 4 x Pi x E. x r^2
What does this symbol mean? E. (E nought).
E. is a constant. It is the primitivity of free space.
What is the equation for the strength of an electric field due to a point charge?
E = Q1 / 4 x Pi x E. x r^2
In which direction does conventional current flow?
Electrons flow from the negative terminal to the positive terminal.
What is the equation for electric field strength that relates potential difference and distance, d.
E = V / D, Electric field strength = Potential Difference / Distance.
Define capacitance.
Capacitance is a capacitors ability to store electrical charge.
What is the equation for capacitance?
C = Q / V, Capacitance = Charge / Potential Difference.
What are the units for capacitance?
C = Q / V, therefore: C V^-1.
What is the equation for work done relating capacitance and potential difference?
W.d. = 1/2 C V^2. This is the area under the line on a capacitance vs potential difference graph.
To what percentage to capacitors lose charge for each unit of time?
64%
What are the three equations for exponential discharge?
Q = Q. x e ^ -t / RC I = I. x e ^ -t /RC V = V. x e ^ -t /RC
What is the order of fingers, from top to bottom, when using Fleming’s left hand rule?
Father, Mother, Child = Force, Magnetic Field, Current.
You have a coil (a current carrying conductor) and a magnet. How do you induce an electromotive force?
Moving the magnet relative to the coil will cause a change in flux linkage and lead to an induced e.m.f. Alternatively, moving the coil relative to the magnet will cause the lines of flux (caused by the magnets magnetic field) to be cut, again, leading to an induced e.m.f.
