Electricity Flashcards
(23 cards)
What is electric current is defined as
The rate of flow of charge
What is the equation for current
Current= charge possible point/time taken
I (amps) = Q (coulomb (C))/T (must be in seconds)
What does voltage measure
Voltage (or potential difference) measures the energy given to components when charges go through them
What is the equation for voltage
Voltage= Energy transfer/charge
V = E (Joules (J))/ Q(coulombs( C))
What happens when you put two bulbs in a series circuit
The Amsterdam because the resistance is greater. The brightness also goes down
-------|||------- | | A1 | | | ---A2--bulb--- | | A3. | | | -----bulb----- What is the relationship between A1, A2 and A3 What happens to the current at the junction
A1=A2+ A3
It is being split (doesn’t have to be even)
What are coulombs
Electrons have a small amount of charge it is measured in coulombs
What is current
The rate of flow of charge
Current= charge/time I= Q/T
What is an amp equal to
1amp = 1 C per second
How is an ammeter placed in a circuit
It is always placed in series with the device
How does an ammeter work
The ammeter records how long it takes for the coulomb to flow through it and then uses the equation: current = charge/time
What is 1 V equal to
One joule per coulomb. This means that one coulomb would have done one joule of electrical energy. The greater the voltage, the greater the amount of energy 1 C of charge has
What will varying the resistance of a variable resistor do
It will vary the potential difference (voltage) across the resistor
What is the equation that links current, voltage and resistance together
Voltage= current x resistance
What does Ohms law state
It states that voltage and current are directly proportional, provided that other physical properties (like temperature) remain constant.
This means that an I-V graph would be a straight line that the passes through the origin
Does a filament lamp obey Ohms law. explain your answer
No. Because the graph is the curve, not a straight line
This is because there is more resistance because the higher temperature of the brighter lamp gives the ions more energy. This is shown because the gradient is getting less
How does resistance vary with light intensity in a light variable resistor
As it gets dimmer, the higher the resistance. It is inversely proportional
How does resistance very with temperature and a thermistor
As the temperature increases, the resistance of a thermistor decreases
Resistance and temperature are inversely proportional
Define electric current
Flow of charges. This is the flow of charge is around the circuit, usually the charge of electrons
- In metal the current is due to electrons flowing from the negative side to the positive side
- Electrolysis, the current consist of positive ions moving to the cathode and negative ions to the anode
Filament lamp
An s shape but without the bit on the end that dips down
Goes through the origin
LDR GRAPH
Current increases as resistant decreases
Through the origin rising to top right
Thermistor graph
Y=1/x
Slopes down from top left to bottom right
Not straight line, curves
Diode graph
Just under 0 in the -ve bit of graph
At 0it raises just above, at 0.7 it sharply increases
