Electrical Engineering Quiz

A power transformer is required to provide an 18V output from a 230V supply. If a secondary current of 1.5A is required, calculate the primary current (assume 100% efficiency).

Calculate the resistance of a 0.6 mm diameter copper conductor having a length of 375m. The specific resistance of copper is 0.017µΩm @ 20°C.

Find, for the circuit below, the applied emf (E).

Find, for the circuit below, the power dissipated in resistor R1.

Show, on the diagram below, the magnetic field patterns around each of the current carrying conductors. Include the: i) polarity of the fields ii) direction of the force acting on the conductors.

Explain briefly one method of reducing each of the following losses in a transformer core: i) Hysteresis losses. ii) Eddy current losses.

An inductor having 720 turns produces a flux of 65 mWb. If the current in the inductor is 1.05 A, calculate the inductance.

For the illustration opposite: name the device.

For the illustration opposite: describe how you would determine the polarity of the device.

For the illustration opposite: draw the BS EN 60617-3:1996 circuit symbol for the device, indicating the polarity.