6. Electromagnetic Induction
рдЗрд╕ рдкреЗрдЬ рдкрд░ рдЖрдкрдХреЛ 6. Electromagnetic Induction рдХреЗ рд╕рднреА рдорд╣рддреНрд╡рдкреВрд░реНрдг рдмрд╣реБрд╡рд┐рдХрд▓реНрдкреАрдп рдкреНрд░рд╢реНрди (MCQ), рдкрд░реАрдХреНрд╖рд╛ рдЙрдкрдпреЛрдЧреА рдиреЛрдЯреНрд╕ рдФрд░ рдСрдирд▓рд╛рдЗрди рдХреНрд╡рд┐рдЬрд╝ рдорд┐рд▓реЗрдВрдЧреЗред рдЕрдкрдиреЗ рдЬреНрдЮрд╛рди рдХрд╛ рдкрд░реАрдХреНрд╖рдг рдХрд░рдиреЗ рдФрд░ рдмреЛрд░реНрдб/рдкреНрд░рддрд┐рдпреЛрдЧреА рдкрд░реАрдХреНрд╖рд╛ рдореЗрдВ рд╢рдд-рдкреНрд░рддрд┐рд╢рдд рдЕрдВрдХ рдкреНрд░рд╛рдкреНрдд рдХрд░рдиреЗ рдХреЗ рд▓рд┐рдП рдиреАрдЪреЗ рджрд┐рдП рдЧрдП рдореЙрдХ рдЯреЗрд╕реНрдЯ рдореЗрдВ рдЕрд╡рд╢реНрдп рднрд╛рдЧ рд▓реЗрдВред
ЁЯСЙ рдЕрдзреНрдпрд╛рдп рдХрд╛ рд╕рд╛рд░рд╛рдВрд╢ (Summary)
Dear students, in this chapter, we will study 1 extremely magical and highly revolutionary branch of physics that literally changed the entire history of human civilization: 'Electromagnetic Induction'. In the previous chapter, we deeply studied how 1 moving electric charge or electric current naturally produces 1 magnetic field around it. But exactly in 1831, 1 brilliant scientist named Michael Faraday asked 1 very logical and reverse question. He thought that if electricity can produce magnetism, then can 1 magnet produce electricity? After conducting continuous experiments for many years, he finally discovered that yes, 1 changing magnetic field can successfully generate 1 electric current in 1 closed circuit. This magnificent phenomenon is scientifically known as Electromagnetic Induction. Today, the massive amount of electricity lighting up our homes, schools, and huge factories is strictly generated based on this single fundamental principle.
Instead of just cramming complex mathematical derivations in closed books, if we logically connect physics with our real life and daily surroundings, it feels extremely fascinating. Have you ever thought deeply about how the giant electric generator inside massive power plants or even 1 small portable generator used during power cuts actually works? Or how exactly your modern induction stove cooks food without any open flame? This is no magic trick, but it is 100 percent the scientific marvel of electromagnetic induction. When 1 massive coil of wire is continuously rotated inside 1 strong magnetic field using giant turbines driven by water or steam, the magnetic flux linked with the coil changes continuously. This continuous change in flux magically induces 1 strong electromotive force (EMF) and current in the coil. Without this phenomenal discovery, we would still be living exactly in the dark ages without any electrical appliances.
From the strict perspective of the upcoming NCERT and RBSE board exams, this specific chapter of physics is highly scoring and extremely important for your 100 percent success. In the board exams, not only direct theoretical questions are asked from this chapter, but excellent analytical, numerical, and derivation-based questions on Faraday's Laws, Lenz's Law, and self-inductance definitely appear in the final exam paper every single year without fail. In this highly exciting journey, we will 1st study the exact mathematical concept of Magnetic Flux very closely, which simply measures the total number of magnetic field lines passing perfectly perpendicular through 1 given surface area.
Moving 1 little further in the chapter, we will logically analyze the 2 extremely powerful laws given by Faraday. We will deeply understand that the magnitude of the induced EMF is exactly equal to the time rate of change of magnetic flux. After this, we will logically study the highly interesting Lenz's Law, which perfectly determines the exact direction of the induced current. Lenz's law basically states that the induced current always flows in such 1 direction that it strictly opposes the very cause that produced it, beautifully confirming the universal law of conservation of energy. We will also learn about Motional EMF, where 1 straight conducting rod moving inside 1 uniform magnetic field acts exactly like 1 battery. Finally, we will deeply understand the crucial concepts of Self-Inductance and Mutual Inductance, which logically explain how 2 separate coils kept near each other can induce current in 1 another.
To perfectly ensure your excellent and 100 percent strong preparation, we have meticulously selected and prepared completely accurate, high-level, and highly exam-useful objective questions (MCQs) from all these complex topics. By continuously practicing again and again, you will surely learn critical time management and massively increase your speed of solving complex numerical questions without making even 1 single mistake.
Feature: This is 1 3-Level based unique quiz. To unlock the next level (Level 2 and 3), students must score at least 70% in the current level, making their board exam preparation 100% strong.
рдорд╣рддреНрд╡рдкреВрд░реНрдг рдкреНрд░рд╢реНрди (Important Questions)
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Unit of Electromotive Force (EMF) is?
A) Newton | B) Joule | C) Volt | D) Ampere -
Self-inductance is also known as?
A) Electrical Inertia | B) Resistance | C) Potential | D) Charge -
Flux in an infinitely long wire with constant current is?
A) Increasing | B) Decreasing | C) Zero | D) Constant -
Self-inductance of a coil depends on?
A) Number of turns | B) Shape of coil | C) Material of core | D) All of the above -
Induced EMF in a conductor moving in a magnetic field is called?
A) Motional EMF | B) Static EMF | C) Thermal EMF | D) Zero -
Example of Mutual Induction is?
A) Bulb | B) Transformer | C) Heater | D) Fan -
Unit of magnetic flux density is?
A) Weber | B) Tesla | C) Henry | D) Volt -
Used to find the direction of induced current?
A) Right hand rule | B) Left hand rule | C) Ohm's law | D) Lenz's law -
What is the SI unit of Magnetic Flux?
A) Tesla | B) Weber | C) Ampere | D) Henry -
What is the unit of Inductance?
A) Weber | B) Ohm | C) Henry | D) Farad -
Lenz's Law is based on the principle of conservation of?
A) Charge | B) Energy | C) Momentum | D) Mass -
Who discovered Electromagnetic Induction?
A) Faraday | B) Oersted | C) Ampere | D) Maxwell -
Eddy currents are produced in?
A) Only conductors | B) Only insulators | C) Both | D) Vacuum -
AC Generator works on the principle of?
A) Photoelectric effect | B) Electromagnetic induction | C) Thermal effect | D) Chemical effect -
Magnetic flux is which type of quantity?
A) Scalar | B) Vector | C) Both | D) None -
Lenz's Law gives the _________ of induced EMF.
A) Magnitude | B) Direction | C) Power | D) Source -
Relation between self-inductance (L) and number of turns (N) is?
A) L тИЭ N | B) L тИЭ N┬▓ | C) L тИЭ 1/N | D) Independent -
Main effect produced by eddy currents is?
A) Cooling | B) Heating effect | C) Light | D) Magnetization -
Induced Charge does NOT depend on?
A) Flux change | B) Resistance | C) Time of change | D) None -
Formula for magnetic energy (U) stored in a coil?
A) 1/2 LI┬▓ | B) LI | C) 1/2 CV┬▓ | D) VIt -
Mutual inductance (M) is maximum when coils are:
A) Parallel | B) Perpendicular | C) Coaxial (over each other) | D) Far apart -
According to Faraday's 2nd law, induced EMF is proportional to:
A) Flux | B) Rate of change of flux | C) Charge | D) Current -
A rod moves parallel to magnetic field, induced EMF will be:
A) Maximum | B) Minimum | C) Zero | D) Constant -
Dimensional formula of magnetic flux is?
A) [ML┬▓TтБ╗┬▓AтБ╗┬╣] | B) [MLTтБ╗┬▓AтБ╗┬╣] | C) [L┬▓A] | D) [ML┬▓TтБ╗┬╣] -
To reduce eddy currents, the core is made:
A) Solid | B) Laminated | C) Hollow | D) Liquid -
Maximum value of coupling coefficient (K) is?
A) 0 | B) 0.5 | C) 1 | D) Infinity -
Self-induction occurs in?
A) One coil | B) Two coils | C) Capacitor | D) Resistance -
Flux is negative when the angle between field and area is:
A) 0┬░ | B) 90┬░ | C) 180┬░ | D) 45┬░ -
Nature of induced electric current is:
A) Transient (momentary) | B) Permanent | C) Zero | D) Infinity -
On increasing inductance, the rate of growth of current:
A) Increases | B) Decreases (Slows down) | C) Remains same | D) Is zero -
If flux changes from 10Wb to 2Wb in 0.2s, induced EMF is?
A) 40V | B) 80V | C) 16V | D) 4V -
EMF of 100V is induced when current drops from 2A to 0 in a 5H coil. Time interval is?
A) 0.1s | B) 0.5s | C) 0.01s | D) 0.10s -
A 2m rod moves perpendicular to 0.5T field at 10 m/s, induced EMF is?
A) 10V | B) 5V | C) 20V | D) 1V -
Stored energy in a 2H coil with 5A current?
A) 10J | B) 25J | C) 50J | D) 5J -
Inductance of 100 turns is 4mH. Inductance of a similar 1000 turn coil is?
A) 40mH | B) 400mH | C) 8mH | D) 0.4mH -
M=0.5H. If current in primary changes at 1A/s, EMF in secondary is?
A) 0.5V | B) 1V | C) 2V | D) 0V -
Flux ╬ж in field B and area A with angle ╬╕ is:
A) BA sin╬╕ | B) BA cos╬╕ | C) B/A | D) A/B -
Flux ╬ж = 6t┬▓ + 7t + 1. Induced EMF at t=2s is?
A) 31V | B) 19V | C) 25V | D) 35V -
Peak value of induced EMF in AC generator is:
A) NBA | B) NBA╧Й | C) N/BA | D) ╧Й/NBA -
If soft iron core is placed inside a coil, self-inductance:
A) Increases | B) Decreases | C) Zero | D) Constant -
On halving the radius of a flat coil, its self-inductance becomes:
A) Half | B) Double | C) One-fourth | D) Constant -
One Henry is equivalent to?
A) Volt-second/Ampere | B) Weber/Ampere | C) Both A & B | D) None -
Eddy currents are used in Moving Coil Galvanometer to make it:
A) Increase current | B) Dead-beat | C) Measure voltage | D) None -
Magnetic energy density per unit volume is:
A) B┬▓/2┬╡тВА | B) ┬╡тВАB┬▓/2 | C) B/┬╡тВА | D) Zero -
Average EMF when a 10cm loop is pulled out of 0.1T field in 0.1s?
A) 0.0314V | B) 3.14V | C) 0.314V | D) 31.4V
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