1 The induced emf in a closed coil of wire, according to Faradays - - PowerPoint PPT Presentation

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1 The induced emf in a closed coil of wire, according to Faraday’s Law, is proportional to: A I B II C II and II D III and IV E IV

• I. The magnitude of the magnetic flux
• II. The magnetic flux density
• III. The number of turns
• IV. The rate of change of magnetic flux

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2 A changing magnetic field B induces an emf Ɛ in a coil of radius R. What is the induced emf in the coil of radius 2R? A ε B 2ε C 4ε D ε /2 E ε /4

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3 A uniform magnetic field is distributed in a space of a circle of radius r. The changing field induces an emf Ɛ in the loop with the radius r. What is the induced emf in the loop with the radius 2r? A ε B 2ε C 4ε D ε /2 E ε /4

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4 The number of turns in a long solenoid is doubled, how does the inductance of the solenoid change? A It doesn't change B It doubles C It quadruples D It is cut to a half E It is cut to a quarter

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5 Which of the following is true about the inductors? A I B III C I and II D II and III E All of the above

• I. They store energy over a long

time

• II. They resist the flow of current

through it

• III. They can produce a magnetic

field

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6 Which of the following can act as an inductor? A I B III C I and II D II and III E All of the above

• I. A long coil
• II. A long wire
• III. A conducting sphere

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7 At time t =0 the switch is closed. Which of the following graphs best describes the voltage V across the resistance R as a function of time t? A B C D E

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8 If L is inductance measured in H (Henry), what is 1 H is equivalent to? A 1 Vs/A B 1 A/Vs C 1 AV/s D 1 As/V E 1 s/AV

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9 If R is 1 Ω and L is 1 H, then L/R is A 1 V B 1 F C 1 A D 1 C E 1 s

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10 In the circuit above, what is the instantaneous current at point P after the switch is closed? A ε/R B 2ε/R C ε/2R D Lε/R E 0

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11 In the circuit above, what is the current at point P after the switch is closed for a long time? A ε/R B 2ε/R C ε/2R D Lε/R E 0

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12 The switch is closed for a long time in the circuit above, what is the energy stored in the inductor? A Lε/2R B Lε2/2R2 C Lε2/2R D Lε/2R2 E L2ε2/2R

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13 An electric circuit consists of a battery of emf Ɛ, a resistor R and an inductor L. Which of the following represents the time constant? A R/L B RL C ε/RL D ε/L E L/R

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14 An electric circuit consists of a battery of emf Ɛ, a resistor R and an inductor L. The circuit has a time constant τ. When another identical resistor R is connected in parallel to the first

• ne, what is the new time constant?

A τ B 2τ C 4τ D τ /2 E τ /4

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15 A resistor R, an inductor L and a battery Ɛ are connected in

• series. Which of the following represents the Kirchhoff’s loop

rule for the given circuit? A B C D E

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16 In the circuit above, initially the switch is open and then it is closed at time t =0. What is the current in the resistor at this time? A 3 A B 1 A C 0 D 0.5 A E 0.3 A

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17 In the circuit above, the switch has been closed for a long time, then it is reopened at time t =0. Which of the following graphs best represents the electric current i as a function of time t? A B C D E

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18 In the circuit above, the switch is closed for a long time. What is the energy stored in the inductor? A 3 J B 6 J C 18 J D 24 J E 36 J

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19 An inductor of inductance of 2 H is connected in series to a resistor of 10 Ω and a 12 V battery. What is the time constant

• f the circuit?

A 5 s B 10 s C 0.2 s D 0.1 s E 0.6 s

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20 An inductor of inductance of 0.4 H is connected in series to a resistor of 6 Ω and a 12 V battery. What is the energy stored in the inductor? A 0.8 J B 1.2 J C 1.8 J D 2.4 J E 3.2 J

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21 In the circuit above, at time t=0 the switch is placed in the position A. What is the current in the resistor at this time? A 0.3 A B 0.6 A C 0 D 3 A E 6 A

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22 In the circuit above, at time t=0 the switch is placed in the position A. What is the voltage across the resistor at this time? A 3 V B 6 V C 9 V D 12 V E 0

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23 In the circuit above, the switch has been kept at the position A for a long time and then at time t=0 is placed at the position B. What is the current in the resistor at this time? A 0.3 A B 0.6 A C 0 D 3 A E 6 A

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24 In the circuit above, a fully charged capacitor with a capacitance C = 25 µF and charge Q = 4 µC is connected to an inductor L = 10 mH? What is the current in the circuit at the instant when the switch is closed? A 1 A B 5 A C 0 D 10 A E 15 A

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25 In the circuit above, a fully charged capacitor with a capacitance C = 25 µF and charge Q = 4 µC is connected to an inductor L = 10 mH? Which of the following occurs after the switch is closed? A The charge instantaneously decreases to zero B The charge expotentially decreases to zero C The charge stays unchanged D The charge oscillate with a period of π ms E The charge oscillate with a period of π μs