Lenz's law

Q1. A coil is connected to a galvanometer. A bar magnet is pushed into the coil. Which statement correctly describes the induced current?

Multiple Choice · 1 point

• · It produces a magnetic field that repels the approaching magnet
• · It produces a magnetic field that attracts the approaching magnet
• · It produces no magnetic field
• · It produces a magnetic field perpendicular to the magnet

Q2. Lenz’s law states that the induced e.m.f. in a circuit is always in a direction that:

Multiple Choice · 1 point

• · Opposes the magnetic field causing it
• · Opposes the current producing the magnetic field
• · Opposes the change in magnetic flux producing it
• · Opposes the resistance of the circuit

Q3. A conducting ring lies in a magnetic field directed into the page. The field strength increases. What is the direction of the induced magnetic field produced by the current in the ring?

Multiple Choice · 1 point

• · Into the page
• · Out of the page
• · Clockwise around the ring
• · Parallel to the plane of the ring

Q4. A magnet is pulled away from a coil. According to Lenz’s law, the induced current in the coil will:

Multiple Choice · 1 point

• · Produce a magnetic field that repels the magnet
• · Produce a magnetic field that attracts the magnet
• · Produce no magnetic field
• · Reverse the magnet’s polarity

Q5. A metal rod moves through a magnetic field while part of a closed circuit. What effect does the induced current have on the motion of the rod?

Multiple Choice · 1 point

• · It accelerates the rod
• · It has no effect on the rod’s motion
• · It produces a force opposing the rod’s motion
• · It produces a force perpendicular to the rod only

Q6. Which fundamental physical principle is satisfied by Lenz’s law?

Multiple Choice · 1 point

• · Conservation of energy
• · Conservation of charge
• · Conservation of momentum
• · Coulomb’s law

Q7. A circular coil is in a magnetic field directed out of the page. The magnetic field strength decreases. The induced current in the coil will be:

Multiple Choice · 1 point

• · Clockwise to produce a field into the page
• · Anticlockwise to produce a field out of the page
• · Zero because the field is decreasing
• · Clockwise to produce a field out of the page

Q8. If Lenz’s law did not apply in electromagnetic induction, what would be possible?

Multiple Choice · 1 point

• · Magnetic flux would remain constant
• · Energy could be created without input work
• · Current would always flow in the same direction
• · Magnetic fields would not exist

Q9. When a coil rotates in a uniform magnetic field, the direction of induced current reverses because:

Multiple Choice · 1 point

• · The resistance of the coil changes
• · The magnetic field disappears periodically
• · The magnetic flux linkage changes sign
• · The number of turns changes

Q10. Magnetic flux through a coil remains constant. What is the induced e.m.f. in the coil?

Multiple Choice · 1 point

• · Maximum
• · Alternating
• · Increasing
• · Zero