Q. A child is sitting on a merry-go-round that is rotating. If the child moves towards the center, what happens to the rotational speed of the merry-go-round?
A.Increases
B.Decreases
C.Remains the same
D.Becomes zero
Solution
As the child moves towards the center, the moment of inertia decreases, causing the rotational speed to increase to conserve angular momentum.
Q. A child is sitting on a merry-go-round that is spinning. If the child moves closer to the center, what happens to the angular velocity of the merry-go-round?
A.Increases
B.Decreases
C.Remains the same
D.Becomes zero
Solution
As the child moves closer to the center, the moment of inertia decreases, causing the angular velocity to increase to conserve angular momentum.
Q. A child is sitting on a merry-go-round that is spinning. If the child moves towards the center, what happens to the angular velocity of the merry-go-round?
A.Increases
B.Decreases
C.Remains the same
D.Becomes zero
Solution
As the child moves towards the center, the moment of inertia decreases, and to conserve angular momentum, the angular velocity must increase.
Q. A child is sitting on a merry-go-round that is spinning. If the child moves towards the center of the merry-go-round, what happens to the angular velocity of the system?
A.Increases
B.Decreases
C.Remains the same
D.Becomes zero
Solution
As the child moves towards the center, the moment of inertia decreases, thus the angular velocity increases to conserve angular momentum.
Q. A child sitting at the edge of a merry-go-round throws a ball tangentially. What happens to the angular momentum of the system (merry-go-round + child + ball)?
A.Increases
B.Decreases
C.Remains constant
D.Becomes zero
Solution
Angular momentum of the system remains constant due to conservation of angular momentum.
Q. A circular loop is placed in a uniform magnetic field. If the loop is rotated about its diameter, what happens to the induced EMF?
A.It increases
B.It decreases
C.It remains constant
D.It becomes zero
Solution
When the loop is rotated about its diameter, the angle between the magnetic field and the normal to the loop changes, but the magnetic flux remains constant. Therefore, the induced EMF becomes zero as there is no change in magnetic flux.
Q. A circular loop of radius R carries a current I. What is the magnetic field at the center of the loop?
A.μ₀I/(2R)
B.μ₀I/R
C.μ₀I/(4R)
D.μ₀I/(8R)
Solution
The magnetic field at the center of a circular loop carrying current I is given by the formula B = (μ₀I)/(2R), where μ₀ is the permeability of free space.
Q. A circular loop of radius r is placed in a uniform magnetic field B. If the magnetic field is perpendicular to the plane of the loop, what is the magnetic flux through the loop?
A.0
B.πr²B
C.2πrB
D.B/r
Solution
The magnetic flux Φ through a surface is given by Φ = B * A, where A is the area. For a circular loop, A = πr², so Φ = B * πr².
Q. A circular loop of wire is placed in a uniform magnetic field. What happens to the induced EMF if the magnetic field strength is doubled?
A.Induced EMF is halved
B.Induced EMF remains the same
C.Induced EMF is doubled
D.Induced EMF is quadrupled
Solution
According to Faraday's law of electromagnetic induction, the induced EMF is directly proportional to the rate of change of magnetic flux. If the magnetic field strength is doubled, the induced EMF will also double.
Q. A circular loop of wire is placed in a uniform magnetic field. What happens to the induced EMF if the area of the loop is increased?
A.Increases
B.Decreases
C.Remains the same
D.Depends on the magnetic field strength
Solution
According to Faraday's law of electromagnetic induction, the induced EMF is proportional to the rate of change of magnetic flux. Increasing the area increases the flux, thus increasing the induced EMF.
