Electricity Flashcards
(66 cards)
What is electric current?
The rate of flow of charge
Electric current refers to the movement of electric charge through a conductor.
What unit is current measured in?
amperes/amps (A)
Amperes (A) is the standard unit for measuring electric current.
In what direction do we take conventional current to go?
Positive to negative
Conventional current is defined as the flow of positive charge from the positive terminal to the negative terminal.
What makes metals good conductors of electricity?
They have delocalised electrons
Delocalised electrons are free to move, allowing metals to conduct electricity efficiently.
What unit is charge measured in?
coulomb (C)
Coulomb (C) is the SI unit of electric charge.
What is the charge on one electron?
1.6 x 10^-19 C
This value is known as the elementary charge.
Write the formula used to connect current and charge.
Q = It
Q represents charge, I represents current, and t represents time.
Write the formula used to calculate the number of electrons flowing.
n = Q / E
n represents the number of electrons, Q is the total charge, and E is the charge on one electron.
What does the letter n represent in the formula n = Q / E?
number of electrons
n indicates how many electrons correspond to the total charge.
What does the letter E represent in the formula n = Q / E?
charge on one electron (C)
E is the elementary charge measured in coulombs (C).
What is used to measure current?
An ammeter
An ammeter is an instrument that measures the flow of electric current.
How must an ammeter be connected into the circuit?
In series
An ammeter must be connected in series to measure the current flowing through the circuit.
What is the rule for current for components in series?
Current is the same through components in series
This means that the same amount of current flows through each component connected in series.
State Kirchoff’s first law (rule for current in parallel).
The sum of the currents entering a point must be the same as the sum of the currents leaving that point
This law applies to junctions in electrical circuits.
What unit is potential difference and EMF measured in?
volt (V)
Both potential difference and electromotive force (EMF) are measured in volts.
Write a definition for EMF.
The emf of a battery is defined as the chemical energy converted into electrical energy when unit charge (1C) passes through it
EMF is essentially the energy provided per unit charge by the source.
Write a definition for potential difference.
The p.d. between two points is the energy generated for every coulomb passing between them
This indicates how much energy is used when a charge moves through a potential difference.
Write an equation linking p.d., energy, and charge.
W = QV or E = QV
This equation relates work done (W), charge (Q), and potential difference (V).
Write what the letters in the equation stand for, and what unit they must be in.
W = work done (J), E = energy transferred (J), Q = charge (C), V = potential difference (V)
Each term must be in the specified units for the equation to hold true.
State Kirchoff’s second law (the rule for voltage in circuits).
The sum of emfs in any closed loop is equal to the sum of potential drops in that loop
This law is fundamental for analyzing electrical circuits.
Write a definition for electrical power.
The rate at which electrical energy is converted into other forms of energy by a circuit or a component in a circuit
This definition highlights the efficiency and conversion of energy in electrical systems.
What unit is power measured in?
Watts (W)
Power is quantified in watts, which indicates the rate of energy transfer.
Write an equation which can be used to calculate power
P = IV
Write what the letters in the equation stand for in P=IV
P = Power (W)
I = Current (A)
V = p.d. (V)
