CBSE Class 10 Science Chapter-13 Magnetic Effects of Electric Current – Free PDF Download
Free PDF download of Important Questions with Answers for CBSE Class 10 Science Chapter 13 – Magnetic Effects of Electric Current prepared by expert Science teachers from latest edition of CBSE(NCERT) books only by CoolGyan to score more marks in CBSE board examination.
CBSE Class 10 Science Chapter-13 Magnetic Effects of Electric Current Important Questions
CBSE Class 10 science Important Questions Chapter 13 – Magnetic Effects of Electric Current
5 Mark Questions
1. Current- time graph from two different sources are shown in the figure.
(i) Name the type of current shown by graph (A) and (B)?
(ii) Name any one source of shown by (A) and (B)?
(iii) What is frequency of current in case (B)?
(iv) Write two difference between current shown by (A) and (B)?
Ans. (i) Graph A represent D.C. and graph B represent A.C.
(ii) Source of (A) – Dry cell
Source of (B) – A.C. generator
(iii) For graph (B)
(iv)
2. Explain the principle, construction and working of an electric motor with a help of labeled diagram?
Ans. Principle – it is based on the principal that a current carrying conductor placed perpendicular to the magnetic field experiences a force.
Construction-
(i) Armature or coil- It consist of an insulated copper wire wound on a soft iron core.
(ii) Strong field magnet- two pole pieces of a strong magnet provides a strong magnetic field.
(iii) Split ring- it consist of two halves 
of a metallic ring which reverses the direction of the current in a coil.
(iv) Brushes- two carbon brushes touch the commutator (split ring).
(v) Battery – a battery is connected across the carbon brushes.
3. Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of split ring in an electric motor?
Ans. Electric motor labelled diagram of an electric motor is as follows:
Principle: A current-carrying conductor, when placed in a magnetic field, experiences a force. If the direction of magnetic field and that of current are mutually perpendicular then force acting on the conductor will be perpendicular to both and will be the given by Fleming’s left-hand rule. Due to this force the conductor begins to move, if it is free to rotate.
Working: Let the current in the coil ABCD of motor enters from the source battery through the conducting brush X, flow along ABCD and finally flows back to the battery through brush Y. On applying Fleming’s left-hand rule we find that force acting on arm AB due to magnetic field pushes it downwards. But the force acting on arm CD pushes it upwards. Thus, the coil and the axle rotate anticlockwise. Due to action of split rings P and Q change their contacts with brushes. Now, P makes contact with Y and Q with X. As a result, Current begins to flow in coil along DCBA. The arms are pushed in opposite direction and coil continues to rotate in same direction.
4.Explain the underlying principle and working of an electric generator by drawing a labeled diagram. What is the function of brushes?
Ans. Electric generator labelled diagram is as follows:
Principle: An electric generator works on the principle of electromagnetic induction.
Working: Let the in the beginnings brushes 
are kept pressed separately on rings 
respectively. Let the axle attached to the rings is rotated such that arm AB of the coil moves up and arm CD moves down in the magnetic field. Due to rotation of arms AB and CD induced current are set up in them. As per Fleming’s right hand rule, induced current in these arms along the directions AB and CD respectively and current flows into.
After half rotation, arm AB moves downward and arms CD upward to change the direction opposite to first case. Thus, after every half rotation current changes its direction and an alternate current is obtained in the generator.
Brushes are kept pressed on the two slip rings separately. Outer ends of the brushes are connected to the galvanometer. Thus, brushes help in transferring current from the coil ABCD to external circuit.