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प्रश्न
State two ways to increase the speed of rotation of a D.C. motor.
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उत्तर
By increasing the magnetic flux [by using strong magnet]
By reducing number of turns in the winding.
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संबंधित प्रश्न
Which of the following property of a proton can change while it moves freely in a magnetic field? (There may be more than one correct answer.)
A current-carrying straight wire is held in exactly vertical position. If the current passes through this wire in the vertically upward direction, what is the direction of magnetic field produced by it? Name the rule used to find the direction of magnetic field.
Name one device whose working depends on the force exerted on a current-carrying coil placed in a magnetic field.
The force experienced by a current-carrying conductor placed in a magnetic field is the largest when the angle between the conductor and the magnetic field is:
45°
60°
90°
180°
Name three factors on which the magnitude of force on a current carrying conductor placed in a magnetic field depends and state how does the force depend on the factors stated by you.
A coil ABCD mounted on an axle is placed between the poles N and S of a permanent magnet as shown in Figure.
- In which direction will the coil begin to rotate when current is passed through the coil in direction ABCD by connecting a battery at the ends A and D of the coil?
- Why is a commutator necessary for continuous rotation of the coil?
- Complete the diagram with commutator, etc. for the flow of current in the coil?
State Fleming’s left-hand rule.
A flat coil ABCD is freely suspended between the pole of a U-shaped permanent magnet with the plane of coil parallel to the magnetic field.
When will coil come to rest?
A flat coil ABCD is freely suspended between the pole pieces of a U-shaped permanent magnet with the plane of coil parallel to the magnetic field.
When will the couple acting on the coil be
- maximum
- minimum?
State under what conditions force acting on a current carrying conductor which is freely suspended in a magnetic field can be maximum.
