Unit 2.2: Resistance Flashcards
Define potential difference
The p.d. between two points is the
amount of electrical energy transferred to
other forms of energy when 1 Coulomb of
charge flows between the points.
The p.d. between 2 points is 6V, what does this mean?
6J of electrical energy is transferred to
other forms of energy when 1 Coulomb of charge flows between the two points.
1 volt is equal to how many joules per coulomb of charge
1
State the equation to transfer volts to joules per coulomb of charge
V=W/Q
What effect does doubling the drift velocity have on the current?
If the drift velocity doubles then the current also doubles.
What causes electrical resistance
Collisions between free electrons and positive ions.
What will a graph of Ohm’s law look like for a metal wire at constant temperature and state the relationship between I and V?
The voltage is directly proportional to the current. Straight line
What will a graph of Ohm’s law look like for a filament bulb?
Curved line.
Initially, the resistance is constant , straight line to begin with.
Then more collisions=temp increases
State ohms law
The current flowing through a metal wire at constant temperature is proportional to the p.d. across it, under constant physical conditions.
State the relationship between Current and Voltage
I∝V
What factors does a resistance of a wire depend on?
The length-double the length=double the resistance
The area-double the area=half the resistance
The material that the wire is made from
Resistivity is a property of a material. What is it defined as?
It is defined as
the resistance of a wire of the material of unit length.
State the equation associated with resistivity
ρ=RA/L
ρ=resistivity
What unit is resistivity measured in?
Ohm meters, Ωm
If the temperature of a wire increases, what happens to the vibrational energy?
The greater the temperature the greater the vibrational energy of the lattice
