Electrical Circuits Flashcards
(21 cards)
Potential difference/voltage across ends of a conductor
The energy transferred per unit electric charge between any two points in a circuit
V=W/Q
V=W/Q
V is Voltage / potential difference
W is transfer of energy
Q is charge in coloumbs
What is emf
The work done per unit charged by the source (battery)
It is equal to the potential difference measured across the terminals of a battery when no charges are flowing in the circuit
Terminal potential difference
The voltage measured across the terminals of a battery when charges are flowing in the circuit
Current strength
The rate of flow of charge
Measured in Ampere(A) which is the same as coloumb per second
What formula can I use to calculate current strength
I =Q/changeintime
What is Q
Q is the symbol for electric charge measured in coulombs
What is the direction of conventional currents
Positive to negative
How do you connect an ammeter correctly
an ammeter must be connected in series with the component you want to measure the current through
How do you connect a voltmeter properly
a voltmeter is connected in parallel with the component you want to measure
Resistance
Resistance is the ratio of the potential difference across a resistor to the current in a resistor
Is measured in ohms and symbol=R
What is ohms law
The potential difference over a resistor is directly proportional to the current flowing in through the resistor , provided the temperature of the resistor remains constant
R = V/I
Ohmic vs non ohmic conductors
Ohmic conductors are materials that follow Ohm’s Law, where voltage and current are directly proportional, meaning the resistance remains constant regardless of the applied voltage or current.
Non-ohmic conductors, on the other hand, do not obey Ohm’s Law, and their resistance varies depending on the voltage and current.
What is resistance
The opposition to the flow of electric charges
Define the unit of resistance
One ohm is equal to one volt per ampere
Microscopic description of Resistance
Electrons move through a conductor colliding with the particles of which the conductor(metal) is made and transferring kinetic energy
What factors affect resistance of a given material
Temperature - increasing temp increases increases resistance because atoms vibrate more when it’s warmer
Length- electrons have to travel further and face more challenges
Thickness-Thicker the wire the less resistance there is because electrons have more space to travel through
What is necessary fir electric current to flow
Source of energy
Closed circuit
Electrical energy
Why does a battery eventually go flat
A battery in a circuit goes flat because the chemical reactions within it, which convert chemical energy to electrical energy, eventually exhaust the available reactants
Resistors in series
Current is the same through each resistor
Siri circuits are potential difference dividers because the total potential difference is equal to the sum of potential differences across all individual components
Calculate the equivalent(total)resistance of resistors connected in series
using Rs = R1 +R2 +….
Resistors in parallel
Potential difference is the same across resistors connected in parallel
Parallel circuits are current dividers because the total current in the circular equal to the sum of the branch circuits
Calculate two resistance of resistance connecting parallel using
1/RP =1/ R1 + 1/R2 +……
