D.2 Electric and magnetic fields SL

Question 1

What is quantisation of electric charge?

Answer 1

Electric charge is quantised, meaning it can only take on discrete values that are multiples of the charge of an electron (1.60 × 10^-19 C).

Question 2

What principle governs the electric charge in an isolated system?

Answer 2

In an isolated system, the principle of charge conservation prevails. This principle dictates that the system’s total charge remains constant over time, highlighting that electric charge cannot be created or destroyed, merely transferred between entities within the system.

Question 3

What happens to electric charge during grounding (earthing)?

Answer 3

During grounding, excess charge is transferred to the Earth, making an object neutral. This process illustrates the conservation of electric charge principle.

Question 4

Describe the effect of a negatively charged comb on paper pieces.

Answer 4

A negatively charged comb can attract neutral paper pieces. The comb repels negative charges in the paper, causing attraction due to the induced positive charge on the paper’s side closest to the comb.

Question 5

Electrostatic induction

Answer 5

Electrostatic induction occurs when a charged object induces a charge distribution in a neighboring neutral object without direct contact, often resulting in opposite charges on the involved objects.

Question 6

Coulomb’s law

Answer 6

Coulomb’s law describes the electrostatic force between two charged objects as directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

Question 7

Coulomb’s law formula

Answer 7

where F is the force between charges, k is the Coulomb constant, *q_

Question 8

What does the Coulomb constant (k) represent?

Answer 8

The Coulomb constant (k) represents the electrostatic force per unit charge, with a value of approximately 8.99 x 10^9 Nm^2/C^2

Question 9

How does the medium between charges affect the electrostatic force?

Answer 9

The medium’s permittivity affects the force; forces decrease in a medium with higher permittivity compared to a vacuum. This is because the medium’s molecules align in a way that reduces the net force between charges.

Question 10

Explain the principle of superposition in Coulomb’s law.

Answer 10

The principle of superposition states that the net electrostatic force on any one charge due to a group of other charges is the vector sum of the forces exerted by each of those charges individually.

Question 11

What defines the strength of an electric field?

Answer 11

Electric field strength is defined as the force per unit charge experienced by a small positive test charge placed in the field.

Question 12

How are electric field lines drawn for positive and negative charges?

Answer 12

For a positive charge, field lines radiate outward; for a negative charge, they converge inward. The density of lines indicates the field’s strength.

Question 13

Describe the electric field between two parallel plates.

Answer 13

Between two parallel plates, the electric field is uniform, meaning the field strength is constant and the field lines are parallel and equidistant.

Question 14

How does the electric field strength vary with distance from a point charge?

Answer 14

Electric field strength decreases with the square of the distance from the charge. Closer to the charge, the field is stronger and the lines are denser.

Question 15

What is the significance of Millikan’s oil drop experiment?

Answer 15

It provided evidence for the quantization of electric charge, demonstrating that charge comes in discrete multiples of the electron’s charge.

Question 16

Magnetic field lines

Answer 16

Magnetic field lines depict the direction and strength of a magnetic field, originating from the north pole and terminating at the south pole, forming closed loops.

Question 17

How does the magnetic field around a straight current-carrying wire appear?

Answer 17

The magnetic field around a straight current-carrying wire forms concentric circles, with the direction determined by the right-hand rule.

Question 18

Describe the magnetic field of a circular coil.

Answer 18

When current flows through a circular coil, the magnetic field resembles that of a bar magnet with a distinct north and south pole.

Question 19

What is the right-hand rule?

Answer 19

The right-hand rule is a method to determine the direction of the magnetic field: thumb points in the current’s direction, and curled fingers show the magnetic field’s direction around the wire.

Question 20

How does the magnetic field of a solenoid compare to that of a bar magnet?

Answer 20

Inside a solenoid, the magnetic field is uniform and similar to the magnetic field of a bar magnet, with a clear north and south pole outside the solenoid.