Circuit symbol for a fixed resistor?
Rectangle
What is electric current? State its units
The rate of flow of charge. Measured in amps.
Give the symbol equation relating charge, current and time
I= q/t
Q=charge(coulombs)
I=current(amps)
T=time(seconds)
In electricity what does ‘e’ represent? What are the units of ‘e’?
Elementary charge
Units are coulombs
What is the value of ‘e’?
1.602x10^-e19
Give two examples of possible charge carriers.
Electrons (in metals) and ions (in electrolytes)
True or false: current flows from negative to positive.
False. Conventional current is the ‘flow of positive charge’- it’s in the opposite direction to the movement of Electra’s in a circuit
How can you measure current in a circuit?
Using an ammeter connected in series with the component
What is kirchhoff’s first law?
All of the current going into a junction is equal to the current leaving the junction. (Charge is conserved)
What is meant by ‘ mean drift velocity’?
The average velocity of the charge carriers due to the applied electric field.it has to be an average because they’re often moving randomly in all directions.
What equation uses the drift velocity to calculate current?
I=Anev
I=current
A=cross sectional area of wire/ conductor
n= number density of charge carriers
e=elementary charge
v=mean drift velocity
What are the units of ‘number density of charge carriers’ in the equation relating current and drift velocity?.
m^-3
Put conductors, semiconductors and insulators in order from highest to lowest number density of charge carriers
Highest: conductors then semiconductors and lowest is insulators
Variable resistor symbol?
A rectangle with a straight diagonal arrow pointing out
What is the name of the component whose circuit symbol is a rectangle with two arrows pointing at it?
Light dependant resistor
Should voltmeters be connected in series or parallel?
Parallel
What is potential difference? State the units
The work done per unit of charge. measured in volts
What’s the difference between voltage and electromotive force?
Voltage is the amount of electrical energy transferred into other forms. Electromotive force is the amount of chemical energy transferred into electrical energy.
Give the equation relating energy transferred to voltage.
W=vq
W=work done
V= potential difference
Q=charge
