Helpmyphysics

An important skill in physics is to rearrange formulas. Click the picture to watch the lesson movie.

The period of a satellite is the time it takes for one complete orbit.

Click the picture to see two satellites orbiting the Earth. Which one has the biggest period.
Determine the periods of each satellite.

For Higher Physics students:

• Determine the period and frequency of the ac supply
• Find the rms voltage of the ac signal

Use this sim to find out about the resistance of combined resistors.

Click the above picture for information on how astronomers detect exoplanets.
Exoplanets are planets orbiting a star outside our solar system.

Click on the picture to help fill in your summary sheet on voltage divider sensors.

A capacitor can be used in a sensor circuit to switch on a transistor after a time interval.
Such a voltage divider circuit will act as a kind of timer.
The time the voltage across the capacitor reaches 0.7 v, to switch on the transistor, can be short or long depending on the size of the capacitance of the capacitor or the size of the resistor its being charged through.

To lengthen the time interval the resistance can be made bigger or the vakue of the capacitor’s capacitance can be made bigger.

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.