Electrical Engineering Answers

At what temperature the saturation current will be the twice of the diode current when the contact potential

At what temperature the saturation current will be the twice of the diode current when the contact potential of the diode is x V. Assuming the diode is made by silicon material.

Two circular loops A and B have their planes parallel to each other.

Loop A has a current moving in the counter clockwise direction, viewed from above.

1. If the current in loop A decreases with time, what is the direction of the induced current in loop B? Will the two loops attract or repel each other?

2. If the current in loop A increases with time, What is the direction of the induced current in loop B? Will the two loops attract or repel each other?

A spherical conducting shell is placed in a time-varying magnetic field. Is there an induced current along the equator?

A spherical conducting shell is placed in a time-varying magnetic field. Is there an induced current along the equator?

Define DC and AC resistance of a diode. Find the DC and AC resistance at

15 μA.

At what temperature the saturation current will be the twice of the diode current

when the contact potential of the diode is 15 V. Assuming the diode is made by

silicon material.

The hot resistance of an incandescent lamp is 10 ohms and the rated voltage is 50 V. Find the resistance required to operate the lamp from an 80 V supply.

a.      At what point in an RLC circuit does resonance occur?       [3marks]

b.     The resonant frequency of a series RLC circuit is 2380kHz when the current is 560 PA and the voltage across it is 240mV. If the value of the inductance in the circuit is 60gH, find the resistance and the capacitance.

[6 marks]

c.      A resistor of 150, an inductor of 0.0318H and a 150uF capacitor are connected in series to a 240V sinusoidal supply at 50Hz. Calculate:

i. The impedance of the whole circuit; [6 marks] ii. The circuit current; [3 marks] iii. The voltage across each component; [4 marks] iv. The power factor;   [3 marks]

A self bias circuit uses Si transistor, RC = 330 Ω, RE = 100 Ω and VCC = 12 V. Estimate the values of R1 and R2 required to provide a base current of 0.3 mA, so as to locate the operating point at ICQ = 18 mA and VCEQ = 4.25 V