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WorksheetsBrushed DC MOTOR and BLDC MOTOR
Total questions: 12
Worksheet time: 11mins
A student carries out an experiment to see the effect of a magnetic field on a wire carrying a current. The wire moves upwards as shown.
What should the student do to make the wire move downwards?
change the direction of the current
move the poles of the magnet closer together
send a smaller current through the wire
use a stronger magnet
A current-carrying coil in a magnetic field experiences a turning effect.
How can the turning effect be increased?
increase the number of turns on the coil
reduce the size of the current
reverse the direction of the magnetic field
use thinner wire for the coil
The diagram shows a simple DC electric motor which is rotating.
Which change will make the motor rotate more quickly?
reversing the polarity of the magnets
reversing the battery
removing the magnets
using more powerful magnets
A simple DC electric motor is fitted with a coil that rotates in a magnetic field. A commutator connects the power supply to the coil.
What is the purpose of the commutator?
It converts AC into DC in the coil.
It prevents the current from becoming too great, because the coil has a low resistance
It reverses the direction of the current in the coil after every 180° rotation of the coil
It switches the current off momentarily after every 90° rotation of the coil
The diagram shows a current-carrying wire placed between two magnetic poles. The current is in the direction shown.
What is the direction of the force on the wire?
towards the bottom of the page
towards the top of the page
towards the left-hand side of the page
towards the right-hand side of the page
WHAT IS BACK EMF?
THE VOLTAGE OPPOSES THE SUPPLY VOLTAGE
THE VOLTAGE DOES NOT OPPOSE THE SUPPLY VOLTAGE
SUPPLY VOLTAGE
Which of the following is not a component of a BLDC motor?
A. Windings
B. Rotor and Stator
C. Commutator
D. Brush
E. Both C and D
Which factors not
affecting the speed of dc motors?
Flux
Current
Applied voltage.
Voltage across the armature
In BLDC motor, Electronic commutation based on __________
Hall position sensors
Temperature sensors
ecoders
THE WORKING PRINCIPLE OF DC MOTOR IS---------
MUTUAL INDUCTION
FLEMING'S RIGHT HAND
LORENTZ LAW
At what speed three-phase cylindrical two-pole synchronous alternator rotates when connected to a 50 Hz infinite busbar system?
1000 rpm
1500 rpm
3000 rpm
6000 rpm
A synchronous motor has _____.
Constant speed
High speed at low torque
Low speed at high torque
Slight drop in speed at full load
