# Can you please explain/make a video on how to answer these questions?

How to show the total resistance of a circuit involving more than one equation and mixed parallel/series circuits when you are given the voltage and resistance for one part of a series graph?
How to show the power dissipated in a (number) resistor
Motor questions of every sort
How to know what directions stuff is going
why is there no current in a cable when something is going at a constant velocity

Hi Sophie,

For total resistance, check out this example, or this one. I’m not sure this is exactly what you’re asking for but if you can direct me to the question you’re thinking of, I’ll either find an existing video, or create a new one for you.

For how to show the power dissipated in a resistor, try this example.

A good example of a motor question can be found here.

For directions, I assume you’re referring to charges, fields etc. Perhaps check out this post and let me know if you need more specific guidance.

Why is there no current in a cable when something is going at a constant velocity? I assume you mean if a coil of wire is moving at a constant velocity inside a magnetic field, if I have misundestood please clarify for me. In the case of a metal coil moving through a magnetic field at constant velocity, to simplify the example let us pretend the coil is a square. Two opposite sides of the square will have charges that are likely to intersect magnetic field lines, so the charges in these sections experience a force from the magnetic field. We can say a voltage is induced in each of these sides of the square. However, as these voltages are both directed (for our example) upwards, and have the same magnitude, the voltages will cancel out, therefore no current is achieved. I realise this is very difficult to convey without diagrams, so please check out this video. This video might also help, (~2.30-3.30) and just be aware there are some L3 concepts included.

I hope this helps.