NCERT Exemplar Solution for CBSE Class 10 Science: Magnetic Effects of Electric Current (Part-II)
In this article you will get CBSE Class 10 Science chapter 13, Magnetic Effects of Electric Current: NCERT Exemplar Problems and Solutions (Part-II). Every question has been provided with a detailed explanation. All the questions given in this article are very important to prepare for CBSE Class 10 Board Exam 2017-2018.
A and there is no change in the deflection of the compass? Under what condition is the deflection maximum and why?
Answer.
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.
Answer.
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?
Answer.
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.
Answer.
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.
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.
Answer.
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?
Answer.
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?
Answer.
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?
Answer.
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?
Answer.
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?
Answer.
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?
Answer.
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.
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NCERT Solutions for Class 9 English Beehive Chapter 11 - If I Were You
Get NCERT Solutions for Class 9 English Beehive Chapter 11 - If I Were You for free PDF download. NCERT solutions help you understand the right criteria to answer the questions in the examinations. We have provided here the precise and comprehensive answers to all questions given in the NCERT Class 9 Beehive Chapter 11. All the answers are explained in a step-by-step manner as per the CBSE guidelines.
Check below the NCERT Solutions for Class 9 English Beehive Chapter 11:
NCERT Solutions
Class 9 English Beehive
Chapter 11 - If I Were You
NCERT Class 9 Beehive Page No. 144
Thinking about the Text
I. Answer these questions.
1. “At last a sympathetic audience.”
(i) Who says this?
(ii) Why does he say it?
(iii) Is he sarcastic or serious?
Answer:
(i) Gerrard says this.
(ii) He says it because the intruder asks him to speak about himself.
(iii) He is being sarcastic.
Also Check: CBSE Class 9 English Syllabus 2020-21
2. Why does the intruder choose Gerrard as the man whose identity he wants to take on?
Answer:
The intruder chooses Gerrard as the man whose identity he wanted to take on because he is of the same build as Gerrard. He is a murderer. As Vincent Charles Gerrard, he will be free to go places and do nothing. He can eat well and sleep without having to be ready to run away at the sight of a cop.
3. “I said it with bullets.”
(i) Who says this?
(ii) What does it mean?
(iii) Is it the truth? What is the speaker’s reason for saying this?
Answer:
(i) Gerrard says this.
(ii) It means that when things went wrong, he had to use his gun to shoot someone to escape.
(iii) No, it is not the truth. He just wants the intruder to believe that he himself is a crook and he has also killed someone and escaped. Thus, the speaker says this to save himself from getting shot by the intruder.
4. What is Gerrard’s profession? Quote the parts of the play that support your answer.
Answer:
Gerrard is a playwright. Some parts of the play that suggest his profession as a playwright are:
- “This is all very melodramatic, not very original, perhaps, but…”
- “At last a sympathetic audience!”
- “In most melodramas the villain is foolish enough to delay his killing long enough to be frustrated”.
- “I said, you were luckier than most melodramatic villains.”
- “That’s a disguise outfit; false moustaches and what not”.
- “Sorry I can’t let you have the props in time for rehearsal, I’ve had a spot of bother – quite amusing. I think I’ll put it in my next play.”
5. “You’ll soon stop being smart.”
(i) Who says this?
(ii) Why does the speaker say it?
(iii) What according to the speaker will stop Gerrard from being smart?
Answer:
(i) The intruder says this.
(ii) The speaker says it to frighten Gerrard as he doesn’t seem to be affected by his (speaker’s) gun.
(iii) According to the speaker, the realisation of being killed will stop Gerrard from being smart.
NCERT Class 9 Beehive Page No. 145
6. “They can’t hang me twice.”
(i) Who says this?
(ii) Why does the speaker say it?
Answer:
(i) The intruder says this line.
(ii) The intruder tells Gerrard that he has already murdered one man and that he will not hesitate to kill him too. Because the police can not hang him twice for two murders.
7. “A mystery I propose to explain.” What is the mystery the speaker proposes to explain?
Answer:
The mystery that Gerrard proposes to explain is a story that he makes to fool the intruder by making him believe that he is also a dangerous man. He tells him that he himself is a criminal. He asks the intruder that why doesn’t he meet any tradespeople and be a bit of a mystery man here today and gone tomorrow. He further adds to the mystery by telling him that the game is up as things went wrong with him when he had to murder someone to escape. Unfortunately, one of his men has been arrested and certain things are found with him which he should have burnt. Gerrard tells the intruder that he is expecting some trouble tonight and therefore, his bag is packed and he is ready to escape.
8. “This is your big surprise.”
(i) Where has this been said in the play?
(ii) What is the surprise?
Answer:
(i) This has been said twice in the play. At first time, the intruder says this to Girrard while revealing his plan to kill him. Secondly, Gerrard says these words when he is about to reveal his fictitious identity to the intruder.
(ii) When intruder says this line, the surprise is his plan to kill Gerrard and take on his identity. On the second occasion, when Gerrard says this, the surprise is his fictitious identity that he is going to reveal to make the intruder believe that he himself is a crook like the intruder.