Chapter 9 - Energy, Power and Resistance Flashcards
What is the difference between Potential Difference and Electromotive Force?
Potential Difference is the work done by the charge carriers
vs
Electromotive force, which is the work done on the charge carriers.
How do you calculate energy transfer using charge?
Energy transfer:
W = VQ, where W is energy in Joules, V is the potential difference and Q is the charge.
W = EQ, where E is electromotive force.
What is the phenomenon, when electrons escape a surface due to the gain in kinetic energy from the heat?
The process of electrons escaping the surface of a material (metal) through the action of heat is called thermionic emission.
What is the equation of resistivity?
R = pL/a Resistance = Resistivity x Length / A
What are the I/V characteristics of a thermistor.
A thermistor is non-ohmic so has a positive and negative exponential line for its graph.
What are the three rules for Circuit Diagrams?
Describe and visualise a switch circuit symbol.
This is an example of an open and closed switch.
Describe and visualise a battery cell circuit symbol. (For single and double configurations).
These are examples of battery cells in two configurations. These are also the polarities.
Describe and visualise a diode circuit symbol.
This is an example of a diode, with the polarities. If the diode is not placed in the direction of conventional current, then it doesn’t let current flow. Diodes are one way.
Describe and visualise a resistor circuit symbol.
This is an example of a resistor symbol.
Describe and visualise a variable resistor circuit symbol.
This is an example of a variable resistor symbol.
Describe and visualise a lamp/bulb circuit symbol.
This is an example of a lamp/bulb circuit symbol.
Describe and visualise a fuse circuit symbol.
This is an example of a fuse symbol.
Describe and visualise a voltmeter circuit symbol.
This is an example of a voltmeter circuit symbol.
Describe and visualise an ammeter circuit symbol.
This is an example of an ammeter symbol.
Describe and visualise a thermistor circuit symbol.
This is an example of a thermistor symbol.
Describe and visualise an LDR circuit symbol.
This is an example of an LDR symbol. LDRs decrease their resistance, with increased light intensity (exponentially).
Describe and visualise a LED circuit symbol.
This is an example of a LED. These are diodes, with one-way polarity.
Describe and visualise a switch circuit symbol.
This is an example of a capacitor symbol.
Define the volt, in terms of Energy and Charge?
1 V = 1 J / C where V is a volt, J is joule, and C is coulomb.
Define the ideal ammeter.
The ideal ammeter has zero resistance, as not to reduce the current in the circuit.
Define an ideal voltmeter.
Define the Ohm, Ω?
What is the equation for electrical power? (In terms of Potential Difference and Current)
What is the equation for electrical power? (In terms of Energy Transferred)
How do electron guns work?
What is the equation of the kinetic energy of an electron?
How does an electron particle accelerator work?
What is Ohm’s law?
What is the gradient equivalent to on a R/L graph (Resistance against Length)?
What is a thermistor?
What is a negative temperature coefficient for electronics?
Semiconductor components have a negative temperature coefficient, meaning their resistance drops as the temperature increases. This is explained as
What is an LDR?
What is the equation for energy transferred (in terms of potential difference, current, and time)?
Define the Kilowatt-hour.
