# Tutor profile: Bryan F.

## Questions

### Subject: Physics (Electricity and Magnetism)

If you have current flowing between two parallel conductors of infinite length, where the currents are equal in magnitude and sign, but flowing in opposite directions to one another, would the two wires repel each other, draw closer to one another, or not move at all?

Assuming two parallel conductors of infinite length, where the currents are equal in magnitude and sign but flowing in opposite directions to one another, the two wires would repel each other. This answer is realized through a simple examination of the current-carrying wires using the "right-hand rule." For reference, the following formula is provided, relating the force per unit length of wire related to current 1 and current 2: $$\frac{F}{\Delta L} = \frac{\mu_0 \cdot I_1 \cdot I_2}{2 \cdot \pi \cdot r}$$ Where F is the magnitude of force, $$\Delta$$ is the length of wire, $$\mu_0$$ is the Magnetic permeability of free-space, $$I_1$$ is the signed current in wire 1, $$I_2$$ is the signed current in wire 2, and $$r$$ is the radial distance between each parallel wire The right-hand rule, in physical terms, is noted by the cross-product below: $$\overrightarrow{F} = \overrightarrow{I}\cdot L \times \overrightarrow{B}$$ where $$\overrightarrow{B}$$ is the expression for a magnetic field, $$\overrightarrow{B} = \frac{\mu_0 \cdot \overrightarrow{I}}{2 \pi r}$$

### Subject: MATLAB

Is MatLab row or column-major?

MatLab is column-major. This means that MatLab elements in the first column of a given matrix are stored together, elements in the second column are stored together, and so forth.

### Subject: Electrical Engineering

When working with an inverter ( a DC/AC converter ), would it be acceptable to implement a switching scheme without any "controlled" dead-time between series switch on/off states?

No, it would not be wise to have a switching converter without any dead-time introduced into your control strategy. Without any dead-time, when each switch in series is turned on when one should normally be off and the other on, your DC/AC inverter would not work as intended and a current shoot-through would occur. Additionally, you introduce opportunities for additional losses, excessive voltage stress across your transistors, thermal stresses, and potentially converter breakdown/shortened reliability.

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