IBPhysicsSLTopic QuestionsFieldsElectric & Magnetic Fields

Syllabus Edition

First teaching 2023

First exams 2025

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Electric & Magnetic Fields (SL IB Physics)

Topic Questions

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1
Sme Calculator1 mark

An electric field is a region of space in which an electric charge is subjected to a force. Electric fields can be represented with vector diagrams showing the direction of force around a point charge.

Select the pair of diagrams which correctly represent the field lines around a positive and negative charge.

  • 5-1-q4-option-a-sl-easy-mcq-phy

  • 5-1-q4-option-bsl-easy-mcq-phy

  • 5-1-q4-option-c-sl-easy-mcq-phy

  • 5-1-q4-option-d-sl-easy-mcq-phy

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2
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5-1-q10-sl-easy-mcq-phy

For electric field strength, identify the correct equation and description of the diagram.

  Equation Description
A. E space equals space F over q The strength of the electric field is proportional to the number of lines per unit cross-sectional area
B. E space equals space F over q The strength of the electric field is indirectly proportional to the number of lines per unit cross-sectional area
C. F space equals space E over q The strength of the electric field is proportional to the number of lines per unit cross-sectional area
D. F space equals space E over q The strength of the electric field is indirectly proportional to the number of lines per unit cross-sectional area

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3
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A current is passed through a wire running vertically upwards through a hole in a flat sheet of card, as shown.

5-4-mcq-7-sl-easy-mcq-phy

Which line correctly describes the induced magnetic field in terms of its direction and orientation relative to the card?

  Direction Orientation to card
A. anti-clockwise same plane
B. anti-clockwise perpendicular
C. clockwise same plane
D. clockwise perpendicular

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4
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A current moves through a solenoid as shown. 

5-4-mcq-8-qun-sl-easy-mcq-phy

Which diagram has the North and South poles of the solenoid, and the magnetic field lines, all correctly marked?

  • 5-4-mcq-8-answer-a-right-sl-easy-mcq-phy

  • 5-4-mcq-8-answer-b-wrong-sl-easy-mcq-phy

  • 5-4-mcq-8-answer-c-wrong-sl-easy-mcq-phy

  • 5-4-mcq-8-answer-d-wrong-sl-easy-mcq-phy

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5
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Which of the following terms best describes the shape of an electric field created by a point charge? 

  • Radial

  • Uniform

  • Inverse

  • Vector

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6
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Which of the following is incorrect regarding the similarities between gravitational and electrostatic fields?

  • The field lines around a point mass and negative point charge are identical

  • The work done in each field is either the product of the mass and change in potential or charge and change in potential

  • The gravitational potential and electric potential both have a 1 over r relationship

  • The gravitational and electrostatic forces are always attractive

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7
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Two parallel metal plates are separated by distance, d and have a potential difference of Ve.

Which equation correctly gives the magnitude of the electric force acting on a stationary charged particle between the plates if the particle has a charge of Q?

  • F equals E over Q

  • F equals k fraction numerator q subscript 1 q subscript 2 over denominator d squared end fraction

  • F space equals space m a

  • F equals space fraction numerator Q V subscript e over denominator d end fraction

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8
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Gravitational and electrostatic forces are similar in many ways. Which statements are correct about both?

  1. Both electrostatic forces and gravitational forces are always attractive
  2. Both electrostatic forces and gravitational forces may be attractive or repulsive
  3. Both electrostatic forces and gravitational forces follow an inverse square law
  4. The equations used to calculate these forces rely on knowing certain universal constants

  • I and III only

  • III and IV only

  • I, II, and III only

  • II, III, and IV only

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1
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An ion of mass m kg carrying a charge of –Q pC travels horizontally with a kinetic energy of Ek = 10 eV. 5-1-sl-mcq-hard-q1-phy

It enters a uniform vertical electric field of strength V kV m–1, which is directed downwards and acts over a horizontal distance of 100 cm.   

Which row in the table below correctly shows the time for the ion to pass through the field, and the magnitude of the force on the ion?

  time / s force
A. fraction numerator square root of m over denominator 4 square root of 10 to the power of negative 19 end exponent end root end fraction

F nN
B. fraction numerator square root of m over denominator 4 square root of 2 square root of 10 to the power of negative 19 end exponent end root end fraction

F nN
C. fraction numerator square root of m over denominator 4 square root of 2 space cross times 10 to the power of negative 19 end exponent end fraction

F µN
D. fraction numerator square root of m over denominator 4 square root of 2 square root of 10 to the power of negative 19 end exponent end root end fraction

F µN

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2
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Point charges, each of magnitude Q are placed at three corners of a square as shown in the diagram.

fVmu8cD3_qu-13

What is the direction of the resultant electric field at the corner with no charge?

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3
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Which one of the following cannot be used as a unit for electric field strength?

  • N A–1 s–1

  • m kg A–1 s–3

  • m kg s–1 C–1

  • J A–1 s–1 m–1 

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4
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What is the electric field pattern between a conducting sphere and an earthed metal plate?

qu-14

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5
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A +1.0 nC and −1.5 nC point charge are placed 6 cm apart at points P and Q. A point R is equidistant to both charges.

5-1-sl-mcq-hard-q5-phy

If an additional charge of +4.0 nC is supplied to both charges, what is the magnitude of the electric field at R and the direction of this field?

  Magnitude of electric field strength Direction of electric field
A. 0.3 k × 10−5 N C−1 Towards X
B. 0.3 k × 10−5 N C−1 Towards Y
C. 0.1 k × 10−11 N C−1 Towards X
D. 0.2 k × 10−13 N C−1 Towards Y

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6
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A student queries their answer after solving some physics problems. The teacher explains that the problem lies in the text book solutions, some of which are incorrect.

An extract from the mark scheme is shown below:

5-1-mcq-h-q6-qun

Without calculation, which answer does the teacher know to be an error?

  • 1.

  • 2a.

  • 2c.

  • 3.

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7
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Electric field strength is defined as 'the electric force per unit charge experienced by a small, positive point charge q'. 

Why is the test charge described as 'small'?

  • Because electrons are small.

  • To obey Coulomb's law for point charges.

  • So that the electric field is not distorted.

  • So that the test charge does not exert a force on other charges in the region.

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8
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The electric potential at different points between two point charges is shown.

5-1-sl-mcq-hard-q8-phy

The electric field strength E varies along the line which connects P and Q.

Which graph correctly shows this variation, where x is the distance along the line PQ?

5-1-sl-mcq-hard-q8_2-phy

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9
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Point charges of +2.0 nC and −3.0 nC are arranged at the corners X and Y of a triangle with sides of 50 mm and 30 mm as shown. 

5-1-sl-mcq-hard-q9-phy

Which is the best estimate for the value of the ratio of the electric field at Z due to X and the electric field due to Y, E subscript X over E subscript Y?

  • 25 over 6

  • 6 over 25

  • 27 over 50

  • 50 over 27

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10
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The diagram shows points X, Y and Z marked on a pattern of electric field lines. The spacing between X and Y and between Y and Z are the same.

5-1-sl-mcq-hard-q10-phy

The potential at X = 0 V and at Y is − 500 V.

What is a likely value for the potential at Z?

  • − 600 V

  • − 850 V

  • − 1000 V

  • − 1200 V

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11
Sme Calculator1 mark

The magnetic field produced by a straight current carrying wire is in

  • a single plane parallel to the current. 

  • all planes parallel to the current.

  • a single plane perpendicular to the current. 

  • all planes perpendicular to the current. 

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12
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A positive charge is placed at S and a negative charge is placed at T. The electric potential at different points between the charges is shown below.

10-1-ib-hl-mcq-q9_1

Which graph correctly shows the variation with x along the line ST of the electric field strength, E?

10-1-ib-hl-mcq-q9-2

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13
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A weighted, positively charged sphere is released from rest, in a vacuum, between two parallel, vertical metal plates one at +100 V and the other grounded. The sphere is initially 4.0 cm from the edge of the grounded plate and 3.0 cm from the bottom of the plates. The sphere takes one of the paths P, Q, R or S and reaches the end of its trajectory in 60 ms.

10-1-ib-hl-mcq-q10

By choosing the correct path, what is the speed of the sphere at the end of its trajectory?

  • 1 over 6 m s–1

  • 5 over 6 m s–1

  • 5 over 3 m s–1

  • square root of 3 over 5 end root m s–1

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1
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Two separated, identical conducting spheres X and Y of charge –8 μC and +12 μC respectively, are brought into brief contact and then separated. What is the final charge distribution on X and Y?

 

X / μC

Y / μC

A.

-8

+12

B.

+10

+10

C.

+2

+2

D.

-4

+6

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2
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A point charge q is placed near a large spherical charge Q = 10q. What is the magnitude of the force experienced by q and Q and the magnitude of the electric field E created by Q at the position of q?

 

Magnitude of force experienced by q

Magnitude of force experienced by Q

Magnitude of E created by Q at position of q

A.

F

F

F over q

B.

10F

0.1F

F over q

C.

F

F

F over Q

D.

0.1F

10F

F over Q

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3
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Two identical point charges q create a resultant electric field at X.

The line XY is a perpendicular bisector of the line joining both point charges.

 q16_electric-fields_ib-sl-physics-mcq

Which vector most accurately depicts the direction of the resultant electric field at X?

  • rightwards arrow

  • upwards arrow

  • leftwards arrow

  • downwards arrow

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4
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Two charges, Q1 = q and Q2 = 4q are separated by a distance r and exert a force of magnitude F on each other. By what factor does the magnitude of the force change if the charge on Q1 doubles and the separation distance trebles?

  • 1 over 9

  • 2 over 3

  • 2 over 9

  • 2

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5
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A plotting compass is placed next to a vertical wire AB. When there is no current in the wire, the compass points North due to an external magnetic field.

q18_magnetic-effects-of-electric-currents_ib-sl-physics-mcq

Which diagram shows a possible direction for the compass to point when a current passes from A to B?

q18_2_magnetic-effects-of-electric-currents_ib-sl-physics-mcq

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6
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A potential difference is applied between two metal plates that are not parallel.

Which diagram shows the electric field between the plates?

10-1-q5

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7
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Two point charges are at rest as shown. Four positions, each of distance r from the nearest point charge, are marked in the image. 

10-1-hl-mcq-medium-q4

At which position is the electric field strength greatest?

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8
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Four point charges, W, X, Y and Z, are fixed to the edges of a square with midpoint O.

10-1-hl-mcq-medium-q9

W, X and Z are negatively charged, and Y is positively charged. What is the direction of the resultant electric field at O? 

  • Towards W

  • Towards X

  • Horizontally right

  • Towards Z

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9
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Two positively charged particles, q1 and q2, are released from rest half-way between two oppositely charged parallel plates in a vacuum. The particles strike the negatively charged plate at the same time. 

10-2-hl-mcq-medium-q9

Neglecting gravitational effects, which of the following statements is correct? 

  • The particles have the same charge only

  • The particles have the same mass only

  • The particles have the same mass and charge

  • The particles have the same charge to mass ratio

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