Electricity P3 Flashcards
How can you charge a rod using cloth
Electrons and protons are attracted to eachother when a cloth is rubbed on a rod is causes friction which will transfer electrons making the material with the new electrons a negative charge and the other positive charge
How does a charged rod move water
The rod that is either positive or negatively charged will attract the proton’s or electrons in the water causing it to move towards the rod
What are electric fields
They are created by electric charges
They can be attractive or repulsive
They exert forces on other charges
Like charges repel and unlike charges attract
Describe how field lines should look in a diagram
Arrows should go from the positive and go to the negative
Arrows should be all around the diagram from positive to negative
Lines never cross
Density of lines show strength of field
What is the unit of energy
Joules are the unit and measurement of energy
What goes parallel and in loop in a simple circuit
Voltmeter has to be parallel to what your measuring
Ammeter has to be in circuit of what it’s measuring
How do you work out the current in a circuit and volts
The total Amps will stay the same all around the circuit
The total volts are shared equally through each component
What happens to the pd and current when in a parallel circuit
The pd across each branch is the same
The current through the battery is the sum of the current through separate branches
Current takes the path of least resistance
Explain a resistors graph
The current is directly proportional to the pd
The resistance is constant
The resistance is constant as the gradient is constant
Explain a bulbs graph
As pd increases so does current but it’s not linear
As the pd increases the temperature increases as ions vibrate more
There are more collisions between the electrons and ions so the resistance increases. This means the current no long increases but levels off
The graph shows the resistance carries because the gradient changes
Explain a diode graph
It’s non linear
For positive pd the resistance is to high so no current flows
Above 0.7 V the resistance falls rapidly so the current increases rapidly
For all the negative values of pd the resistance is extremely high so no current flows
Diodes are used to protect computers which would be damaged if the power supply was connected the wrong way
What’s ohms law
The current is directly proportional to the pd
What’s the electrical current
It’s the rate of flow of charge
Charge = current x time
What’s energy transferred
The PD is the energy transferred per coulomb of charge
Energy= charge x PD
What is power
Power is the rate energy transferred (energy transferred per second)
Power = energy/time
