NEET Physics · Flashcards
This deck has 22 flashcards on Electromagnetic Induction & Alternating Currents for NEET Physics, from NCERT Class 12. It covers the NCERT chapters Electromagnetic Induction and Alternating Current.
Master Electromagnetic Induction and AC for NEET: High-yield flashcards covering Faraday's Law, LCR Resonance, Transformer ratios, and Phasor dynamics
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Card 1 of 22
State Faraday's Law of Electromagnetic Induction.
Hint: The negative sign is explained by Lenz's Law.
Answer
The magnitude of the induced EMF in a circuit is directly proportional to the rate of change of magnetic flux linked with the circuit. e = - dΦ/dt
Card 2 of 22
State Lenz's Law and its underlying conservation principle.
Hint: If a North pole approaches a coil, the coil face becomes a North pole to repel it.
Answer
Opposes the cause: Approaching N-pole induces anti-clockwise (N) current to repel.
Card 3 of 22
What is the formula for Motional EMF induced in a straight conductor moving in a uniform magnetic field?
Hint: The moving conductor acts like a battery. Force required to keep it moving: F = B²l²v / R.
Answer
e = B v l (Provided B, v, and l are all mutually perpendicular). General form: e = Bvl sin(θ).
Card 4 of 22
What are Eddy Currents and how can their energy loss be minimized?
Hint: Applications include magnetic braking in trains, induction furnaces, and speedometers.
Answer
Eddy currents are circulating currents induced in bulk pieces of metal when subjected to a changing magnetic flux. Minimized by using laminated metallic cores (thin sheets separated by insulation).
Card 5 of 22
Write the formula for the Self-Inductance (L) of a long solenoid.
Hint: Depends purely on the geometry of the coil and the core medium (L = μ₀μ_r n² A l).
Answer
L = μ₀ n² A l = μ₀ N² A / l Where 'n' is turns per unit length (N/l), 'A' is cross-sectional area, and 'l' is length.
Card 6 of 22
What is the formula for the Potential Energy (U) stored in an inductor?
Hint: Energy is stored in the form of a Magnetic Field (analogous to ½ C V² in capacitors).
Answer
U = ½ L I² Where L is inductance and I is the current.
Card 7 of 22
What is the relation between the Mutual Inductance (M) of two coils and their individual Self-Inductances (L₁, L₂)?
Hint: k=1 for perfectly coupled coils (wound over each other). k=0 for perpendicular coils.
Answer
M = k √(L₁ L₂) Where 'k' is the coefficient of coupling (0 ≤ k ≤ 1).
Card 8 of 22
What is the relationship between Peak (I₀) and RMS (Iᵣₘₛ) values of Alternating Current?
Hint: RMS value is the 'effective' value used for calculating average power and heat dissipation. Standard household 220V is an RMS value.
Answer
Iᵣₘₛ = I₀ / √2 ≈ 0.707 I₀ Vᵣₘₛ = V₀ / √2 ≈ 0.707 V₀
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