cameroon gce advanced level 2025 electrical machines 1
cameroon gce advanced level 2025 electrical machines 1
- The motor used in railway drive and traction purposes is
- A. Series motor
- B. Universal motor
- C. Shunt motor
- D. Compound motor
- The voltage regulation of a transformer is
- A.
- B.
- C.
- D.
- The quantity that does not change in a transformer?
- A. current
- B. voltage
- C. frequency
- D. power
- In direct current machines, mechanical losses are primarily a function of
- A. current
- B. voltage
- C. speed
- D. torque
- A straight conductor having an active length of 20cm is kept in a uniform magnetic field of 0.5T. The emf induced in the conductor, when it moves at the rate of 5m/s and its motion is perpendicular to the magnetic field is
- A. 0V
- B. 0.5V
- C. 0.25V
- D. 0.45V
- A three phase, two pole synchronous motor with 50Hz frequency. The synchronous speed will be
- A. 1500rpm
- B. 3000rpm
- C. 750rpm
- D. 1000rpm
- The reason for which synchronous motors are not self-starting is
- A. The direction of rotation is not fixed
- B. The direction of instantaneous torque reverse after half cycle
- C. Starts cannot be used on these machines
- D. Starting winding is not provided on the machine
- In the left-hand rule, the forefinger always represents
- A. Voltage
- B. Current
- C. Magnetic field
- D. Direction of force on the conductor
- In a capacitor start and run motor, the function of the running capacitor in series with the auxiliary winding is to
- A. Improve power factor
- B. Increase overload capacity
- C. Reduce fluctuations in torque
- D. To improve torque
- Mostly, synchronous motors are of
- A. Alternator type machine
- B. Induction type machine
- C. Salient pole type machine
- D. Smooth cylindrical type machine
- The magnetizing current of a transformer core is usually small due to
- A. Small air gap
- B. Large leakage flux
- C. Laminated silicon steel core
- D. Fewer rotating part
- A permanent magnet
- A. Attract some substances and repels others
- B. Attract all paramagnetic substances and repels others
- C. Attracts only ferromagnetic substances
- D. Attracts ferromagnetic substances and repels all others
- The number of brushes in a commutator depends on
- A. Speed of armature
- B. Type of winding
- C. voltage
- D. Amount of current to be collected
- The force between two charges is 120N. If the distance between the charges is doubled, the force will be
- A. 60N
- B. 30N
- C. 40N
- D. 15N
- The flux per square unit area is
- A. Magnetic Reluctance
- B. Magnetic field strength
- C. Magnetic flux density
- D. Magnetomotive force
