Quiz-14 ELECTROMAGNETIC INDUCTION

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ELECTROMAGNETIC INDUCTION Quiz-14

Dear Readers,

As per analysis for previous years, it has been observed that students preparing for NEET find Physics out of all the sections to be complex to handle and the majority of them are not able to comprehend the reason behind it. This problem arises especially because these aspirants appearing for the examination are more inclined to have a keen interest in Biology due to their medical background. Furthermore, sections such as Physics are dominantly based on theories, laws, numerical in comparison to a section of Biology which is more of fact-based, life sciences, and includes substantial explanations. By using the table given below, you easily and directly access to the topics and respective links of MCQs. Moreover, to make learning smooth and efficient, all the questions come with their supportive solutions to make utilization of time even more productive. Students will be covered for all their studies as the topics are available from basics to even the most advanced. .

Q1. Voltage in the secondary coil of a transformer does not depend upon

•  Voltage in the primary coil
•  Ratio of number of turns in the two coils
•  Frequency of the source
•  Both (a) and (b)

Solution
It is a fact.

Q2. The current carrying wire and the rod AB are in the same plane. The rod moves parallel to the wire with a velocity v. Which one of the following statements is true about induced emf in the rod 

•  End A will be at lower potential with respect to B
•  A and B will be at the same potential
•  There will be no induced e.m.f. in the rod
•  Potential at A will be higher than that at B

Solution
By Fleming’s right hand rule

Q3.  A copper disc of radius 0.1 m is rotated about its centre with 10 revolutions per second in a uniform magnetic field of 0.1 tesla with its plane perpendicular to the field. The e.m.f. induced across the radius of disc is

•  π/10 V
•  2π/10 V
•  π×10^-2V
•  2π×10^-2V

Solution
e= 1/2 Bωr²=1/2×0.1×2π×10×0.1²=π×10^-2V

Q4.  In which of the following circuit is the current maximum just after the switch S is closed 

•  (i)
•  (ii)
•  (iii)
•  Both (ii) and (iii)

Solution
At t=0 current through L is zero so it acts as open circuit. The given figures can be redrawn as follow 

Q5. O is the centre of two coplanar concentric circular conductors, A and B, of radii r and R respectively as shown in the figure. Here,r <<<R  the mutual inductance of the system of the conductors can be given by 

•  (μ₀ π^r2)/2R
•  (μ₀ π^R2)/2r
•  (πR²)/(μ₀ r)
•  (μ₀ πr)/2R

Solution
 Mutual inductance for two concentric coplanar circular coils,

Q6. Two identical coaxial circular loops carry current i each circulating in the clockwise direction. If the loops are approaching each other, then

•  Current in each loop increases
•  Current in each loop remains the same
•  Current in each loop decreases
•  Current in one-loop increases and in the other it decreases

Solution
According to Lenz’s Law.

Q7. The core of a transformer is laminated to reduce

•  Flux leakage
•  Output power
•  Hysteresis
•  Eddy current

Solution
It is a fact.

Q8. In circular coil, when no. of turns is doubled and resistance becomes 1/4 th of initial, then inductance becomes

•  4 times
•  2 times
•  8 times
•  No change

Solution
L∝N²

Q9. Lenz’s law is statement of

•  Law of conservation of charge
•  Law of conservation of current
•  Law of conservation of energy
•  None of the above

Solution
Lenz’s law restates the law of conservation of energy.

Q10.  A coil of area 100cm² has 500 turns. Magnetic field of 0.1 weber/metre² is perpendicular to the coil. The field is reduced to zero in 0.1 second. The induced e.m.f in the coil is

•  1 V
•  5 V
•  50 V
•  Zero

Solution