Advertisements
Advertisements
Question
Draw and label the diagram of a simple D.C. motor.
(a) Explain the rotation of the coil, giving a reason for your answer.
(b) How can you reverse the direction of rotation of the armature?
(c) How can you increase the speed of rotation of the motor?
Advertisements
Solution
(a) The coil rotates because equal and opposi te forces act on its arms which form a couple.
(b) The direct ion of rotation of armature can be reversed by interchanging the connections at the terminals of the battery joined to the brushes of the motor.
(c) The speed of rotation of the motor can be increased by increasing the current through the coil or by increasing the number of turns in the coil and by increasing the strength of the magnetic field.
APPEARS IN
RELATED QUESTIONS
Name two devices in which electromagnets are used and two devices where permanent magnets are used.
How is the working of an electric bell affected, if alternating current be used instead of direct current?
A light metal disc on the top of an electromagnet is thrown up as the current is switched on. Why? Give reason.
Fill in the blanks by writing (i) Only soft iron, (ii) Only steel, (iii) Both soft-iron and steel for the material of core and/or magnet.
A. C. generator______.
The magnetic flux passing through a coil perpendicular to its plane is a function of time and is given by OB = (2t3 + 4t2 + 8t + 8) Wb. If the resistance of the coil is 5 Ω, determine the induced current through the coil at a time t = 3 second.
There is a uniform magnetic field directed perpendicular and into the plane of the paper. An irregular shaped conducting loop is slowly changing into a circular loop in the plane of the paper. Then ______.
Which of the following instruments works by electromagnetic induction?
The working of a dynamo is based on the principle of
A current I = 10 sin(100π t) A is passed in first coil, which induces a maximum e.m.f of 5π volt in second coil. The mutual inductance between the coils is ______.
