Electromagnetic Induction & AC · JEE Main previous year questions

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2024 13 questions

Q592024 · 9 Apr 2024 · Shift 1· Numerical answer
When a coil is connected across a $20 V$ dc supply, it draws a current of $5 A$ . When it is connected across $20 V$ , $50 Hz$ ac supply, it draws a current of $4 A$ . The self inductance of the coil is ______ $mH$ . (Take $π = 3$ )
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Answer: 10
Q382024 · 6 Apr 2024 · Shift 2
In a coil, the current changes from $- 2 A$ to $+ 2 A$ in $0.2 s$ and induces an emf of $0.1 V$ . The self inductance of the coil is :
1. A. $4 mH$
2. B. $2.5 mH$
3. C. $1 mH$
4. D. $5 mH$
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Answer: D
Q512024 · 6 Apr 2024 · Shift 2· Numerical answer
For a given series LCR circuit it is found that maximum current is drawn when value of variable capacitance is $2.5 nF$ . If resistance of $200 Ω$ and $100 mH$ inductor is being used in the given circuit. The frequency of ac source is ________ $\times 1 0^{3} Hz$ (given $π^{2} = 10$ )
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Answer: 10
Q382024 · 5 Apr 2024 · Shift 2
A series LCR circuit is subjected to an ac signal of $200 V, 50 Hz$ . If the voltage across the inductor ( $L = 10 mH$ ) is $31.4 V$ , then the current in this circuit is ____.
1. A. $10 A$
2. B. $10 mA$
3. C. $68 A$
4. D. $63 A$
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Answer: A
Q582024 · 5 Apr 2024 · Shift 2· Numerical answer
The current in an inductor is given by $I = (3 t + 8)$ where $t$ is in second. The magnitude of induced emf produced in the inductor is $12 mV$ . The self-inductance of the inductor ____ $mH$ .
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Answer: 4
Q582024 · 4 Apr 2024 · Shift 1· Numerical answer
An alternating current at any instant is given by $i = [6 + 56 sin (100 π t + π /3)] A$ . The rms value of the current is ____ $A$ .
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Answer: 8
Q332024 · 4 Apr 2024 · Shift 2
1. A.A-IV, B-I, C-III, D-II
2. B.A-I, B-IV, C-II, D-III
3. C.A-IV, B-I, C-II, D-III
4. D.A-I, B-IV, C-III, D-II
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Answer: B
Q482024 · 1 Feb 2024 · Shift 2
A transformer has an efficiency of $80%$ and works at $10 V$ and $4 kW$ . If the secondary voltage is $240 V$ , then the current in the secondary coil is :
1. A. $1.33 A$
2. B. $13.33 A$
3. C. $1.59 A$
4. D. $15.1 A$
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Answer: B
Q582024 · 31 Jan 2024 · Shift 1· Numerical answer
A small square loop of wire of side $l$ is placed inside a large square loop of wire of side $L (L = l^{2})$ . The loops are coplanar and their centers coincide. The value of the mutual inductance of the system is $x \times 1 0^{- 7} H$ , where $x =$ ____.
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Answer: 128
Q482024 · 31 Jan 2024 · Shift 2
An AC voltage $V = 20 sin 200 π t$ is applied to a series LCR circuit which drives a current $I = 10 sin (200 π t + \frac{π}{3})$ . The average power dissipated is:
1. A.21.6 W
2. B.200 W
3. C.173.2 W
4. D.50 W
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Answer: D
Q452024 · 30 Jan 2024 · Shift 1
1. A. $\frac{2 μ _{0} I}{a}$
2. B. $\frac{μ _{0} I}{2 a}$
3. C. $\frac{μ _{0} I}{2 a}$
4. D. $\frac{2 μ _{0} I}{a}$
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Answer: B
Q532024 · 27 Jan 2024 · Shift 1· Numerical answer
Two coils have mutual inductance $0.002 H$ . The current changes in the first coil according to the relation $i = i_{0} sin ω t$ , where $i_{0} = 5 A$ and $ω = 50 π rad/s$ . The maximum value of emf in the second coil is $\frac{π}{α} V$ . The value of $α$ is ________.
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Answer: 2
Q522024 · 27 Jan 2024 · Shift 2· Numerical answer
A series LCR circuit with $L = \frac{100}{π} mH$ , $C = \frac{1 0 ^{- 3}}{π} F$ and $R = 10Ω$ , is connected across an ac source of $220 V, 50 Hz$ supply. The power factor of the circuit would be _______.
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Answer: 1