electric circuits Flashcards
what is a variable resistor
a variable resistor is a resistor where you are able to change the resistance
what is a thermistor
The resistance of a thermistor depends on its temperature. At low temperatures, the thermistor has a high resistance. As the temperature increases, the resistance decreases. A
thermistor can be used heat activated fire alarms. its symbol is line with a base at the bottom left
What is a light-dependent resistor?
The resistance of a LDR depends on light intensity. At low light levels, the LDR has a high resistance as it generates electricity with high resistance. As the light intensity increases, the resistance decreases. A
LDR
can be used as a sensor in cameras or automatic lights that come on when it gets dark. The symbol is a a circle inside a box with two small arrows on the top left corner
what are the two types of current? and describe the difference
direct and alternating. In a
direct current the flow of
electrons is consistently in one direction around the circuit. In an alternating current the direction of electron flow continually reverses.
what is the equation for charge?
charge = current × time
charge (Q) is measured in coulombs (C)
current (I) is measured in amps (A)
time (t) is measured in seconds (s)
what is current and potential difference measured in? where ae they located in a circuit?
Current is measured using an
ammeter. To measure the current through component, the ammeter must be placed in series with that component. To measure the potential difference a voltmeter must be placed
in parallel with that component
what is potential difference?
Potential difference (or voltage) is a measure of energy, per unit of charge, transferred between two points in a circuit. A potential difference of 1 volt means that 1 joule of work is done per coulomb of charge.
what is the equation for potential difference?
potential difference = energy
________
charge
what is the equation for potential difference relating to resistance?
potential difference = current × resistance
what are the two factors that effect resistance in a practical?
- the length of the wire
2.the thickness of the wire
what is a random error?
a random error is an error that a can be addressed by repeating and taking more measurements to calculate the mean-it can be due human errors in measuring ,the wrong use of equipment such as using timer -the difference in reaction time for each student.it can also be caused by variations of conditions such as the room temperature.
what is a systematic error?
if a measurement is wrong by the same amount ever time it called a systematic error, Repeating the experiment the same exact way and calculating a mean wont correct a systematic error
explain the current, potential difference ad resistance in a series circuit
in a series circuit the current is the same everywhere in the loop. the potential difference is shared across the components because the total energy for each charge from the power source goes into driving the current through all components . Energy is transferred to each component proportional to its resistance.in a series circuit the total resistance is the sum of all individual resistors
explain the current, potential difference and resistance in a parallel circuit.
in a parallel circuit the total current is split between the components on different loops as when a charge reaches a junction it splits. the potential difference in a parallel circuit is the same as the charge still carries the same amount of energy. the resistance in parallel circuits is reduced as the current may follow multiple paths.
what is the equation or energy transferred?
energy transferred =
charge flow times* potential difference
