Q. If a magnetic field is applied perpendicular to a loop of wire, what is the effect on the induced EMF?
A.It is maximum
B.It is minimum
C.It is zero
D.It fluctuates
Solution
When a magnetic field is applied perpendicular to a loop of wire, the magnetic flux through the loop is maximized, resulting in maximum induced EMF according to Faraday's law.
Q. If a magnetic field is directed into the page and a positive charge moves to the right, what is the direction of the magnetic force acting on the charge?
A.Into the page
B.Out of the page
C.Upward
D.Downward
Solution
Using the right-hand rule, point your thumb in the direction of the velocity (to the right) and your fingers in the direction of the magnetic field (into the page). Your palm will face out of the page, indicating the direction of the force.
Q. If a wire is bent into a semicircular shape, what is the magnetic field at the center of the semicircle due to current I?
A.μ₀I/(4R)
B.μ₀I/(2R)
C.μ₀I/(πR)
D.μ₀I/(8R)
Solution
The magnetic field at the center of a semicircular wire carrying current I is given by B = μ₀I/(4R) for the semicircle, which is half of the full circular loop.
Q. If the angle between the current element and the line joining the current element to the point of interest is 90 degrees, what is the contribution of that current element to the magnetic field?
A.Maximum
B.Minimum
C.Zero
D.Undefined
Solution
If the angle is 90 degrees, the sine of the angle is zero, resulting in zero contribution to the magnetic field from that current element.
Q. If the current in a circular loop is doubled, how does the magnetic field at the center of the loop change?
A.It remains the same
B.It doubles
C.It quadruples
D.It halves
Solution
The magnetic field at the center of a circular loop is directly proportional to the current; thus, if the current is doubled, the magnetic field also doubles.
Q. If the current in a coil is doubled, the magnetic field strength around the coil will?
A.Double
B.Halve
C.Remain the same
D.Increase by four times
Solution
The magnetic field strength around a coil is directly proportional to the current, so if the current is doubled, the magnetic field strength will also double.
Q. If the current in a wire is doubled, how does the magnetic field at a point 5 cm away from the wire change?
A.It doubles
B.It quadruples
C.It remains the same
D.It halves
Solution
According to Biot-Savart Law, the magnetic field is directly proportional to the current. Therefore, if the current is doubled, the magnetic field also doubles.
Q. If the current in a wire is doubled, how does the magnetic field at a point near the wire change?
A.It remains the same
B.It doubles
C.It quadruples
D.It halves
Solution
According to the Biot-Savart Law, the magnetic field is directly proportional to the current, so if the current is doubled, the magnetic field also doubles.