Question 4
- With the aid of a diagram, explain Fleming’s Left-Hand Rule with respect to motors.
- A d.c. shunt generator connected across a 30 V supply has an armature current of 20 A and an armature resistance of 0.7Ω. Calculate the generated voltage
Observation
The expected answers were;
- Diagram explaining Fleming’s Left-Hand Rule with respect to motors.
OR
VT = Va - IARA
When a left hand is held with the thumb, forefinger and middle finger mutually perpendicular, if the forefinger points in the direction of a magnetic field and the middle finger points in the direction of the current flowing through a conductor within the field, then the conductor moves in the direction of the thumb.
(b) Calculation of the generated voltage
VT = Va - IARA
Va= VT + IARA
VT = Va - IARA
= 30 + (20*0.7)
Va = 44V
Many of the candidates that attempted this question did fairly well. However, some could not draw the diagram to explain Fleming’s Left Hand-Rule. Very few could not calculate the generated voltage.