CBSE 12th Standard Physics Subject Moving Charges And Magnetism 5 Mark Ncert Exemplar Questions 2021
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CBSE 12th Standard Physics Subject Moving Charges And Magnetism 5 Mark Ncert Exemplar Questions 2021
12th Standard CBSE
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Reg.No. :
Physics
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Explain using a labelled diagram, the principle and working of a moving coil galvanometer. What is the function of
(i) uniform radial magnetic field
(ii) soft iron core?
Also, define the terms
(iii) current sensitivity and
(iv) voltage sensitivity of a galvanometer.
Why does increasing the current sensitivity not necessarily increase voltage sensitivity?(a) -
Ms. Kanchan, a student of PG course in nanotechnology lab in IIT Kanpur on her first day in the lab met Mr. Cobra, the lab assistant
He advised her not to touch the wires, which were suspended from the roof at every part of the lab as they were from high voltage lines.
He also told her not to bring any of the two wires closer to each other during any experimental applications. Read the above passage and answer the following questions:
(i) What values did Mr. Cobra exhibit? Give two reasons.
(ii) Why should not the the two high voltage wires be brought close to each other?(a) -
In the birthday party of Kamal, his parents gave big slinkies to all his friends as a return gift. The very next day, during the physics class Mr. Mohan, the teacher explained them about the production of magnetic field using current carrying coil and also said that they can make permanent magnet, using such coils by passing high currents through them. That night Priyanshu, a friend of Kamal, asked his father about the coils, and their shape. His father asked him to bring the slinky, that his friend gave and explained the use of toroid and solenoid.
Read the above passage and answer the following questions:
(i) What value did Priyanshu's father have?
(ii) What is the difference between solenoid and toroid?
(iii) Give the value or magnitude of magnetic field in solenoid.(a) -
Niyaz was using galvanometer in the practical class. Unfortunately, it fell from his hand and broke. He was upset, some of his friends advised him not to tell the teacher but Niyaz decided to tell his teacher. Teacher listened to him patiently and on knowing that the act was not intentional, but just an accident, did not scold him and used the opportunity to show the internal structure of galvanometer.
(i) What are the values displayed by Niyaz?
(ii) Give the principle of moving coil galvanometer.
(iii) How can you increase the sensitivity of a galvanometer?(a) -
(i) Derive the expression for the torque on a rectangular current carrying loop suspended in a uniform magnetic field
(ii) A proton and a deuteron having equal momentum enter in a region of a uniform magnetic field at right angle to the direction of the field.Depict their trajectories in the field(a)
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CBSE 12th Standard Physics Subject Moving Charges And Magnetism 5 Mark Ncert Exemplar Questions 2021 Answer Keys
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Current sensitivity, \({ I }_{ s }=\frac { NAB }{ k } \) and
Voltage sensitivity, \(V_{ s }=\frac { NAB }{ kR } \)
Since, the resistance of the coil may vary, it implies an increase in current sensitivity may not necessarily increase voltage sensitivity.
Thus, the trajectory of both the particles will be same. -
(i) He exhibits responsible behaviour, sensitivity and concern for others.
(ii) Because the two wires have high magnetic field around them. -
(i) Priyanshu's father is responsible, makes his child understood the concepts of solenoid and toroid.
(ii) A solenoid has magnetic field straight within the turns and in toroid, it is in form of concentric circles.
(iii) The magnitude of magnetic field in solenoid is given by \(B={ { \mu } }_{ \circ }nI\)
(where, n = number of turns/length, I = current in coil) -
(i) Niyaz shows the values of courage to tell truth and determination.
(ii) It is based on the principle when a current carrying coil placed in external magnetic field, it develops torque.
(iii) Sensitivity of galvanometer can be increased by
(a) increasing number of turns in the coil and
(b) by increasing current in the coil. -
(ii) We know, Lorentz force, F = Bqv sin\(\theta \)
Where \(\theta \) = angle between velocity of particle and magnetic field=900
So,Lorentz force, F = Bqv [sin 900 = 1]
When a charged particle enters in a magnetic field in a direction normal to the field, then in this condition,
Lorentz force = Centripetal force
\(Bqv=\frac { mv^{ 2 } }{ r } \Rightarrow r=\frac { mv }{ Bq } \)
