Here you get the CBSE Class 10 Science chapter 13, Magnetic Effects of Electric Current: NCERT Exemplar Problems and Solutions (Part-II). This part of the chapter includes solutions for Question No. 13 to 24 from the NCERT Exemplar Problems for Class 10 Science Chapter: Magnetic Effects of Electric Current. These questions include only the Short Answer Type Questions framed from various important topics in the chapter. Each question is provided with a detailed explanation.
NCERT Exemplar problems are a very good resource for preparing the critical questions like Higher Order Thinking Skill (HOTS) questions. All these questions are very important to prepare for CBSE Class 10 Science Board Examination 2017-2018 as well as other competitive exams.
Find below the NCERT Exemplar problems and their solutions for Class 10 Science Chapter, Magnetic Effects of Electric Current:
Short Answer Type Questions
Question 13. A magnetic compass needle is placed in the plane of paper near point A as shown in figure. In which plane should a straight current carrying conductor be placed so that it passes through A and there is no change in the deflection of the compass? Under what condition is the deflection maximum and why?
We know that when the magnetic field and the direction of current are perpendicular to each other, the deflection is maximum. But when they are in the same plane, no deflection takes place.
If we place the current carrying conductor in the plane of paper such that it passes through A then, the field produced by it is perpendicular to the plane of paper and parallel to the vertical axis of compass needle. As a result there will be no change in the deflection of compass needle..
Deflection in compass needle will be maximum when the conductor passes through A and is perpendicular to the plane of paper.
Question 14. Under what conditions permanent electromagnet is obtained if a current carrying solenoid is used? Support your answer with the help of a labelled circuit diagram.
The following conditions are required to obtain permanent electromagnet when a current carrying solenoid is used:
1. Rod inside the solenoid should be made of magnetic material like steel which should retain magnetic properties for a long time after magnetization.
2. The current through the solenoid should be direct current.
3. The number of turns in the solenoid should be large and closely packed, so that a strong uniform magnetic field inside it is produced.
Question 15. AB is a current carrying conductor in the plane of the paper as shown in figure. What are the directions of magnetic fields produced by it at points P and Q? Given r1 > r2, where will the strength of the magnetic field be larger?
By applying Right-hand thumb rule, the direction of Magnetic field is into the plane of the paper at P and coming out from the plane of paper at the point Q.
The magnitude of magnetic field B is inversely proportional to distance r.
Now r1 > r2, or point Q is closer than point P, so the magnetic field is stronger at point Q and weaker at point P.
Question 16. A magnetic compass shows a deflection, when placed near a current carrying wire. How will the deflection of the compass get affected, if the current in the wire is increased? Support your answer with a reason.
Magnetic field (B) produced by current-carrying wire is directly proportional to the current (I) flowing through the wire.
If the current is increased then the magnetic field produced is stronger and vice-versa. So, deflection in the compass will be more when the current flowing through the wire will be increased.
Question 17. It is established that an electric current through a metallic conductor produces a magnetic field around it. Is there a similar magnetic field produced around a thin beam of moving (i) alpha particles, (ii) neutrons? Justify your answer.
Magnetic field is produced by a current carrying conductor due to the motion of charge particles or electron.
(i) As, alpha particles are positively charged so there movement will also produce magnetic field.
(ii) Neutrons do not carry any charge so their motion will not produce any magnetic field
Question 18. What does the direction of thumb indicate in the right-hand thumb rule? In what way this rule is different from Fleming's Left-hand rule.
According to right-hand thumb rule, the thumb shows the direction of electric current as shown in the figure given below.
The curled fingers holding the conductor give the direction of magnetic lines.
Fleming's left-hand rule gives the direction of force experiences by a current carrying straight conductor placed in an external magnetic field and here thumb represent force on conductor.
Question 19. Meena draws magnetic field lines of field close to the axis of a current carrying circular loop. As she moves away from the centre of the circular loop she observes that the lines keep on diverging. How will you explain her observation?
We know that the magnetic field produced by a current-carrying straight wire depends inversely on the distance from it. Similarly at every point of a current-carrying circular loop, the concentric circles representing the magnetic field around it would become larger and larger as we move away from the wire. By the time we reach at the centre of the circular loop, the arcs of these big circles would appear as straight lines. Every point on the wire carrying current would give rise to the magnetic field appearing as straight lines at the center of the loop.
Due to this reason, as she moves away from the centre of the circular loop she observes that the lines keep on diverging.
Question 20. What does the divergence of magnetic field lines near the ends of a current carrying straight solenoid indicate?
Divergence of magnetic field lines near the ends of a current carrying straight solenoid indicates decrease in the strength of the magnetic field.
Question 21. Name four appliances wherein an electric motor, a rotating device that converts electrical energy to mechanical energy, is used as an important component. In what respect motors are different from generators?
The four appliances are: electric juicer, electric fan, walkman, washing machine.
The motor is a device which converts the electric energy into mechanical energy, whereas generator converts mechanical energy into electrical energy.
Question 22. What is the role of the two conducting stationary brushes in a simple electric motor?
The role of carbon brushes is to make contact with the rotating rings of the commutator and through them to supply current to the coil.
Question 23. What is the difference between a direct current and an alternating current? How many times does AC used in India change direction in one second?
The direction of the AC (alternating current) reverses periodically whereas the direction of the DC (direct current) remains constant with time. The frequency of AC in India is about 50 Hz whereas of DC it is zero.
Therefore, in India AC change its direction after every 1/100s So, in one second AC changes its direction 100 times.
Question 24. What is the role of fuse, used in series with any electrical appliance? Why should a fuse with defined rating not be replaced by one with a larger rating?
Fuse is the most important safety device, used for protecting the circuits due to short-circuiting or overloading of the circuits.
The use of an electric fuse prevents the electric circuit and the appliance from a possible damage by stopping the flow of unduly high electric current. The Joule heating that takes place in the fuse melts it to break the electric circuit. So, a fuse is always connected in series with an appliance. If it is connected in parallel then it will not be able to break the circuit and current keeps on flowing.
When a fuse with defined rating for a particular appliance is replaced by one with larger rating, then it will not melt as the current exceeds in the wire and short-circuiting or overloading may occur.