Helpmyphysics

Use this sim to determine the relationship between the voltage across a resistor and the current passing through it.
Notice the variable resistor will vary the current in the circuit.

Take current and voltage readings in a table and plot a graph current in the x-axis and voltage in the y-axis.

A thermistor is a resistor whose resistance changes with temperature.
When it becomes cold its resistance gets bigger. When it becomes hot its resistance becomes smaller.

Check the voltages across the voltage divider.
The mosfet acts like a switch. When the voltage at its gate becomes bigger than 2 volts it will switch on the relay which in turn switches the fan on.

Click the picture to go to the sim.

Some questions:

1. What do you notice about the variable resistor’s voltage as its resistance increases?
2. What do you notice about the sum of the voltages across the resistors?
3. For each resistor in turn, take the ratio of voltage across it and divide by the resistance. What do you notice?

Click here for the simulation of a light dependent transistor being used to0 turn on a LED when it gets dark.

Here is a quiz for you to try on the topic of radiation.
The answers to the quiz will appear shortly.
Best of luck!

Isaac Newton thought this experiment up about firing a cannon ball from a cannon.

Check out this movie. Roll your mouse over Isaac`s picture to get more info.

[kml_flashembed movie=”http://www.helpmyphysics.co.uk/NewtonsCannon.swf” height=”450″ width=”550″ /kml]

Here is a presentation on satellites.

[kml_flashembed movie=”http://www.helpmyphysics.co.uk/geostationary.swf” height=”450″ width=”550″ /kml]

Roll your mouse over each of the members of the electromagnetic spectrum and find out how they are detected and used.

[kml_flashembed movie=”http://www.helpmyphysics.co.uk/em_spectrum.swf” height=”450″ width=”550″ /kml]

Use this downloadable sheet to record your research. Research sheet