Electricity and Magnetism — Free IB MYP5 Physics Questions

1QuestionForce acting on current carrying wire in external magnetic fieldConcept Practice

2 marks~3 minCriterion D

An electric motor in a washing machine contains a current-carrying coil placed inside a magnetic field.

a

Explain how the magnetic force acting on the current-carrying coil produces rotation inside the electric motor. [1]

b

Explain one societal benefit that washing machines, powered by electric motors, provide to communities. [1]

Solutions

2QuestionForce acting on current carrying wire in external magnetic fieldConcept Practice

3 marks~5 minCriterion A

A student investigates the force on a current-carrying wire in a uniform magnetic field of strength

B = 0.2\ \text{T}

. The length of wire inside the field is

L = 0.15\ \text{m}

. The student varies the current

I

and records the force

F

. The graph of

F

against

I

is a straight line passing through the origin.

a

State the equation relating

F

,

B

,

I

, and

L

, and calculate the gradient of the graph. [1]

b

Explain why the graph is a straight line through the origin. [1]

c

The student doubles the length of wire inside the field while keeping

B

and

I

constant. Analyse how this change affects the gradient of a new

F

–

I

graph. [1]

Solutions

3QuestionDangers of Overloading and Short CircuitsConcept Practice

2 marks~3 minCriterion A

A student plugs a 2 kW heater, a 1.8 kW kettle, and a 1.2 kW microwave into a single extension cord rated at 13 A. The mains supply is 230 V.

a

Calculate the total current drawn by all three appliances. [1]

b

The extension cord's current rating is exceeded. Explain why this creates a fire hazard and how a circuit breaker prevents it. [1]

Solutions

4QuestionDangers of Overloading and Short CircuitsConcept Practice

1 mark~2 minCriterion A

A household circuit contains a live wire, a neutral wire, an appliance, and a protective component labelled X. Component X is connected in series with the appliance on the live wire.

(a) Identify component X, which melts and breaks the circuit when excessive current flows. [1]

Solutions

5QuestionCharging by Friction Induction and ConductionConcept Practice

2 marks~3 minCriterion A

When a wool cloth is rubbed against a plastic rod, electrons transfer from the wool to the rod, as shown in the diagram.

a

State the type of charge acquired by the plastic rod after rubbing. [1]

b

The wool cloth is now held near (but not touching) a small, uncharged metal sphere suspended on a nylon thread. Explain how the sphere becomes polarised. [1]

Solutions

6QuestionAdvantages and Applications of Each TypeConcept Practice

2 marks~3 minCriterion D

A homeowner observes that when one light bulb in their living room ceiling fixture burns out, the other bulbs stay lit. However, in a string of old holiday lights, a single burned-out bulb makes the entire string go dark. Identify one positive societal impact of using parallel circuits instead of series circuits for home lighting.

Solutions

7QuestionCurrent and Voltage in Series CircuitsConcept Practice

4 marks~6 minCriterion C

A series circuit in a school laboratory contains a 9 V battery, resistor

R_1

, and resistor

R_2

. A student measures the voltage drop across

R_1

as 3.5 V.

a

State the relationship between the supply voltage and the individual voltage drops across components in a series circuit. [1]

b

Calculate the voltage drop across

R_2

. [1]

c

A second student records voltmeter readings of 6 V across

R_1

and 4 V across

R_2

. Evaluate whether these readings are consistent with the 9 V supply, and justify your reasoning using the relationship from part (a). [2]

Solutions

8QuestionAdvantages and Applications of Each TypeConcept Practice

2 marks~3 minCriterion A

A series circuit contains a 6 V battery, a switch, and three identical bulbs connected in series.

a

Identify the component that controls whether current flows in this circuit. [1]

b

Explain what happens to the bulbs when this component is opened. [1]

Solutions

9QuestionCalculating Resistance in Series and ParallelConcept Practice

1 mark~2 minCriterion D

A student uses a 20 m long extension cord made of thin copper wire to connect a 1500 W space heater to a wall outlet. The resistance of the cord causes the voltage at the heater to be lower than the outlet voltage, reducing the heater's power output. Identify one negative societal impact of this voltage drop.

a

The heater operates more efficiently at lower power.

b

Energy is wasted as heat in the extension cord, increasing electricity costs.

c

The extension cord becomes cooler, reducing fire risk.

d

The heater lasts longer due to reduced power.

Solutions

10QuestionOhms Law V = IRConcept Practice

2 marks~3 minCriterion C

The graph below shows voltage (V) on the y-axis and current (I) on the x-axis for a fixed resistor. Describe the relationship between V and I using scientific language. Include the terms 'directly proportional' and 'Ohm's law', and explain what the gradient of the line represents.

Solutions

11QuestionMagnetic Field Around a Bar MagnetAssessment Practice

4 marks~6 minCriterion A

A student places a plotting compass at five positions around a bar magnet, labelled P, Q, R, S, and T, as shown in the diagram. At positions P and S (near the north pole) the needle points away from the magnet; at Q and T (near the south pole) it points toward the magnet; at R (beside the midpoint) it aligns parallel to the magnet's length.

a

Explain why the compass needle points in a different direction at each position, referring to magnetic field lines and the magnet's poles. [2]

b

The compass positions are closer together near the poles than near the midpoint. Explain what this spacing suggests about field line density and field strength at those regions. [1]

c

Evaluate one limitation of using a plotting compass to map the complete magnetic field of a bar magnet. [1]

Solutions

12QuestionField Lines Around Straight Current carrying conductors and SolenoidsAssessment Practice

4 marks~6 minCriterion B

A straight wire carries a steady current. A sensor records the magnetic field strength

B

at three fixed distances from the wire:

r = 1\ \text{cm}

,

r = 3\ \text{cm}

, and

r = 9\ \text{cm}

. The graph shows

B

against time for each distance; the curves are labelled A (

r = 1\ \text{cm}

), B (

r = 3\ \text{cm}

), and C (

r = 9\ \text{cm}

).

a

State which curve shows the strongest magnetic field and identify its distance from the wire. [1]

b

Explain how the graph shows that magnetic field strength depends on distance from the wire. [2]

c

The distances follow the pattern

1\ \text{cm}

,

3\ \text{cm}

,

9\ \text{cm}

(each three times the previous). Analyse what this pattern, combined with the relative field strengths shown, suggests about the mathematical relationship between

B

and

r

. [1]

Solutions

13QuestionField Lines Around Straight Current carrying conductors and SolenoidsAssessment Practice

5 marks~8 minCriterion C

A student investigates the magnetic field inside a solenoid of length

L = 0.50

m with

N = 500

turns. The magnetic flux density

B

(in mT) is measured at the centre for different currents

I

(in A).

I

(A): 0.5, 1.0, 1.5, 2.0, 2.5, 3.0

B

(mT): 1.26, 2.51, 3.77, 5.03, 6.28, 7.54

The magnetic field inside a solenoid is

B = \mu_0 n I

, where

n = N/L

.

a

Convert

B

to tesla (T). Construct a graph of

B

(T) against

I

(A), draw a line of best fit, and calculate its gradient. [2]

b

Deduce an experimental value for

\mu_0

using your gradient and the solenoid dimensions. [2]

c

The accepted value is

\mu_0 = 4\pi \times 10^{-7}

T·m/A, giving a percentage error of approximately 100%. Analyse one source of systematic error that could cause this result and explain how the experimental setup could be modified to reduce it. [1]

Solutions

14QuestionMagnetic Materials / Temporary and Permanent MagnetsAssessment Practice

2 marks~3 minCriterion D

A scrapyard crane uses an electromagnet to sort ferromagnetic scrap metal. The electromagnet consists of a coil of wire wound around a soft-iron core.

a

Explain how switching the current on and off allows the electromagnet to lift and then release scrap metal. [1]

b

Evaluate why replacing the electromagnet with a permanent magnet would make the crane impractical for this task. [1]

Solutions

15QuestionField Lines Around Straight Current carrying conductors and SolenoidsAssessment Practice

5 marks~8 minCriterion B

A long, straight wire carries a constant current. The magnetic field strength (

B

) is measured at several distances (

r

) from the wire.

Distance from wire (cm)	1	2	3	4	5
Magnetic field strength ( $\mu$ T)	100	50	33.3	25	20

a

Deduce the mathematical relationship between

B

and

r

using the data provided. [1]

b

Show that the percentage decrease in

B

when

r

increases from 1 cm to 3 cm is approximately 66.7%. [1]

c

A solenoid is formed by winding the same wire into a series of closely spaced loops. Analyse why the magnetic field inside the solenoid is significantly more uniform than the field around the straight wire. [3]

Solutions

16QuestionMagnetic Field Around a Bar MagnetAssessment Practice

4 marks~6 minCriterion C

The diagram shows a bar magnet with four compass positions:

Position A — near the north pole
Position B — near the south pole
Position C — at the side of the magnet, midway between the poles
Position D — far from the magnet, in the same horizontal plane

a

Explain the orientation of the compass needle at positions A, B, and C, stating the direction of the magnetic field line at each position. [2]

b

Justify which single position (A, B, C, or D) has the strongest magnetic field. [1]

c

A student claims the field at C is weaker than at D because "the poles cancel at the midpoint." Evaluate this claim. [1]

Solutions

17QuestionDangers of Overloading and Short CircuitsAssessment Practice

6 marks~9 minCriterion B

A student investigates how current affects the time for wire insulation to melt. Five wires of different gauges are tested; each carries a fixed current until its insulation melts.

Current (A)	15	10	6	4	2.5
Time to melt (s)	5	12	30	60	120

a

On the axes provided, construct a graph of time to melt (vertical axis) against current (horizontal axis). [2]

b

Deduce a mathematical rule linking time to melt and current. Show the calculations you used to arrive at your rule. [2]

c

A fuse wire in a household circuit carries 8 A. Evaluate whether this wire's insulation will melt within 20 seconds, using your rule and the pattern in the data. [2]

Solutions

18QuestionEarth Wires and Electrical GroundingAssessment Practice

3 marks~5 minCriterion A

The graph below shows touch voltage versus time for a faulty metal-cased appliance in which a live wire contacts the casing. Two curves are plotted: one without an earth wire and one with an earth wire connected. In the earthed scenario, the touch voltage drops to near zero within milliseconds of the fault occurring.

Explain why the touch voltage drops to near zero when the earth wire is present. [3]

Solutions

19QuestionDangers of Overloading and Short CircuitsAssessment Practice

4 marks~6 minCriterion C

V–I Characteristics

A resistor and a filament lamp are each connected in turn to a variable power supply. The current through each component is recorded as the voltage across it is increased from zero. The results are displayed on a V–I graph, with voltage on the horizontal axis and current on the vertical axis.

a

Describe the shape of the V–I curve for the filament lamp. [1]

b

Identify which component is ohmic and explain what property of its V–I graph confirms this. [1]

c

Using the V–I graph, explain how and why the resistance of the filament lamp changes as the voltage increases. [2]

Solutions

20QuestionDangers of Overloading and Short CircuitsAssessment Practice

3 marks~5 minCriterion D

The graph below shows how current

I

varies with resistance

R

in a circuit maintained at a constant voltage of 12 V.

a

State Ohm's Law and rearrange it to express

I

in terms of

V

and

R

. [1]

b

Explain the shape of the graph using your expression from part (a). [1]

c

Identify the region of the graph where a short circuit would occur and analyse why this region represents a serious electrical hazard. [1]

Solutions

21QuestionDangers of Overloading and Short CircuitsAssessment Practice

8 marks~12 minCriterion D

A homeowner replaces an old fuse box with a modern circuit breaker panel. The breakers contain neodymium, a rare-earth metal essential to their tripping mechanism. Neodymium mining in a developing country has caused severe river pollution and health problems for nearby communities. The homeowner is aware of these harms but prioritises family safety.

a

Explain how a circuit breaker reduces the risk of electrical fires and electric shock during a short circuit or overload. [2]

b

Describe the environmental and social harms caused by neodymium mining, as presented in this scenario. [2]

c

Evaluate whether the homeowner's decision is ethically justified, considering both the safety benefits for their family and the negative impacts on distant communities. [4]

Solutions

22QuestionDangers of Overloading and Short CircuitsAssessment Practice

4 marks~6 minCriterion C

Fuse Protection

A phone charger is connected to a 230 V mains socket and draws a current of 0.13 A. Available fuse ratings for this circuit are 3 A, 5 A, and 13 A.

a

Calculate the power consumed by the charger. Use

P = VI

. [1]

b

Explain how a fuse protects a circuit, linking the physical process inside the fuse to the safety outcome for the circuit. [2]

c

A student argues that a 13 A fuse is acceptable because it will not blow during normal operation. Evaluate this claim, using the current drawn by the charger to support your reasoning. [1]

---

Solutions

23QuestionCharging by Friction Induction and ConductionAssessment Practice

3 marks~5 minCriterion A

A student charges a gold-leaf electroscope positively, then touches its top plate with a finger at

t = 0

s. The graph shows leaf angle against time for two conditions.

Dry finger: leaf angle decreases from

30°

at

t = 0

s to

10°

at

t = 10

s.
Moist finger: leaf angle decreases from

30°

at

t = 0

s to

0°

at

t = 4

s.

a

State what the decreasing leaf angle indicates about the charge on the electroscope. [1]

b

Explain why touching the plate with a finger causes the leaf angle to decrease. [1]

c

Explain why the leaf angle decreases more rapidly with a moist finger than a dry finger. In your answer, refer to electrical resistance and the rate of electron transfer. [1]

Solutions

24QuestionElectric Field Concepts IntroductoryAssessment Practice

5 marks~8 minCriterion C

In an experiment, a student measures the electric field strength

E

(in N/C) at several distances

r

(in metres) from a small charged sphere. The data are plotted with

E

on the y-axis and

\dfrac{1}{r^2}

(in m

^{-2}

) on the x-axis. The graph is a straight line through the origin with gradient

8.99 \times 10^{3}

N m

^{2}

C

^{-1}

.

The electric field around a point charge is given by

E = k\dfrac{Q}{r^2}

, where

k = 8.99 \times 10^{9}

N m

^{2}

C

^{-2}

.

a

Show that the equation

E = k\dfrac{Q}{r^2}

can be written in the linear form

y = mx

, and identify the gradient in terms of

k

and

Q

. [1]

b

Calculate the magnitude of the charge

Q

. [2]

c

The sphere is replaced by a second sphere carrying a charge of

-4.00\ \mu

C, placed at the same location. Analyse how the electric field strength at a fixed distance

r

would differ from your result in (b), and explain what the negative sign indicates about the field. [2]

Solutions

25QuestionCharging by Friction Induction and ConductionAssessment Practice

7 marks~11 minCriterion D

An electrostatic precipitator (ESP) removes smoke particles from exhaust gases in a coal-fired power plant. Gas passes through a chamber containing a high-voltage wire and oppositely charged collector plates. As a smoke particle approaches the wire, it becomes negatively charged by induction and is subsequently attracted to the positively charged collector plates.

a

Explain how a neutral smoke particle becomes negatively charged by induction as it approaches the high-voltage wire. [2]

b

Explain why the negatively charged particle moves toward the collector plate rather than returning toward the wire. [2]

c

Evaluate the effectiveness of an ESP when the collector plates are coated with a thick layer of high-resistivity dust and gas flow rate through the chamber is significantly increased. [3]

Solutions

26QuestionCharging by Friction Induction and ConductionAssessment Practice

6 marks~9 minCriterion D

Coal-fired power plants use electrostatic precipitators (ESPs) to reduce particulate pollution. Inside an ESP, exhaust gases pass between a negatively charged wire and grounded collection plates. Dust particles enter the strong electric field, become charged, and are drawn to the plates, where they accumulate and are periodically removed. ESPs can capture up to 99% of particulate matter, yet they consume significant electrical power and generate toxic solid waste containing heavy metals such as lead and mercury.

a

Explain the process by which dust particles become charged inside an ESP and are subsequently removed from the exhaust gases. [2]

b

Analyse the trade-off between the air-quality benefits of ESP operation and its associated energy costs. [2]

c

Evaluate whether ESPs provide a comprehensive solution to coal-plant pollution, identifying one specific limitation in your response. [2]

Solutions

27QuestionElectric Field Concepts IntroductoryAssessment Practice

5 marks~8 minCriterion A

Two point charges are fixed in a vacuum:

q_1 = +3.0 \times 10^{-6} \, \text{C}

and

q_2 = -5.0 \times 10^{-6} \, \text{C}

, separated by

0.20 \, \text{m}

. Point

P

lies exactly halfway between them. A student measures the electric field at

P

as

1.8 \times 10^6 \, \text{N/C}

directed toward

q_2

.

Use

E = k\dfrac{|q|}{r^2}

, where

k = 8.99 \times 10^9 \, \text{N m}^2 \, \text{C}^{-2}

.

a

Calculate the electric field strength at

P

due to each charge. [2]

b

Deduce the net electric field at

P

, stating both magnitude and direction. [1]

c

Evaluate whether the student's measured value is consistent with your result in (b), identifying the most likely source of the discrepancy. [2]

Solutions

28QuestionCharging by Friction Induction and ConductionAssessment Practice

5 marks~8 minCriterion C

A student uses an electroscope to investigate electrostatic charging. Three trials are conducted with a negatively charged plastic rod and an uncharged electroscope.

Trial 1: The rod is held near (not touching) the metal cap. The gold leaves diverge, then return to their original position when the rod is removed.

Trial 2: The rod touches the metal cap. The leaves diverge and remain diverged after the rod is removed.

Trial 3: The rod touches a neutral metal sphere; the sphere is then held near (not touching) the cap. The leaves diverge, then return when the sphere is removed.

a

Identify the charging method demonstrated in Trial 1 and Trial 2. [2]

b

Explain, using charge transfer and charge distribution, why the leaves remain diverged in Trial 2 but return to their original position in Trial 1. [2]

c

Evaluate the extent to which these three trials provide valid evidence for the standard electrostatic model of charging. In your response, discuss what Trial 3 demonstrates and identify limitations that affect the validity of the conclusions. [1]

Solutions

29QuestionAdvantages and Applications of Each TypeAssessment Practice

12 marks~18 minCriterion A

A student investigates the internal resistance of a battery by connecting it to a variable resistor. Terminal voltage

V

is recorded for several values of current

I

, and the results are plotted on a

V

–

I

graph. The graph is a straight line passing through the points

(0.2\ \text{A},\ 1.4\ \text{V})

and

(0.8\ \text{A},\ 1.1\ \text{V})

, with a

y

-intercept at

1.5\ \text{V}

.

a

Deduce the internal resistance

r

of the battery using the graph. Show all working. [4]

b

The relationship between terminal voltage and current is given by

V = \mathcal{E} - Ir

. Using your results from (a), calculate the electromotive force

\mathcal{E}

and explain how the graph confirms your answer. [4]

c

A student claims that internal resistance does not matter as long as the external resistance is large. Evaluate this claim, referring to terminal voltage, power loss, and a practical circuit context. [4]

Solutions

30QuestionAdvantages and Applications of Each TypeAssessment Practice

4 marks~6 minCriterion B

The diagram shows a circuit with a 12 V battery, a single bulb (resistance 6 Ω), and a variable resistor set to 4 Ω, all in series. An ammeter reads the current in the circuit.

a

[2 marks] Predict the new reading on the ammeter when a second identical bulb (6 Ω) is added in parallel to the first bulb. Justify your prediction by explaining the effect on total resistance and current division.

b

[2 marks] Predict how the brightness of the original bulb changes when the second bulb is added in parallel. Justify your prediction.

Solutions

31QuestionConstructing Simple Electrical CircuitsAssessment Practice

8 marks~12 minCriterion C

A student builds a circuit using a 12 V battery and three identical bulbs — X, Y, and Z — connected in series. Using a digital ammeter, the student records the current at three positions: before bulb X (2.1 A), between bulbs X and Y (2.0 A), and after bulb Z (1.9 A). A voltmeter measures the voltage across each bulb: X (3.8 V), Y (3.9 V), Z (3.7 V).

a

Calculate the total voltage across the three bulbs. Using the formula below, calculate the percentage difference between this total and the battery voltage. [2]

\text{Percentage difference} = \frac{\text{Measured voltage} - \text{Battery voltage}}{\text{Battery voltage}} \times 100

b

Using the formula below, calculate the percentage difference between the highest and lowest current readings. [2]

\text{Percentage difference} = \frac{\text{Highest current} - \text{Lowest current}}{\text{Average current}} \times 100

c

Evaluate whether the data support the conclusion that this is a true series circuit. In your response, apply Kirchhoff's voltage and current laws, reference your results from (a) and (b), and assess the role of measurement errors. [4]

Solutions

32QuestionAdvantages and Applications of Each TypeAssessment Practice

5 marks~8 minCriterion D

A student builds a series circuit using a 3.0 V battery, a 10

\Omega

resistor

R_1

, and a 5.0

\Omega

resistor

R_2

. Measurements give a current of 0.19 A and a terminal voltage of 2.85 V across the battery. The student claims these results do not align with the ideal series circuit model.

Evaluate the validity of this claim.

a

Calculate the total resistance predicted by the ideal series circuit model. [1]

b

Deduce the measured total resistance of the circuit using Ohm's law and the measured values. [1]

c

Analyse the discrepancy between the terminal voltage (2.85 V) and the rated voltage (3.0 V). In your analysis, calculate the internal resistance of the battery and evaluate whether the student's claim is correct. [3]

Solutions

33QuestionCurrent and Voltage in Parallel CircuitsAssessment Practice

7 marks~11 minCriterion B

Analyze the current distribution in a parallel circuit with three branches. The circuit has a voltage source that can be adjusted to 6 V, 9 V, 12 V, and 18 V. The three branches contain resistors of 2 Ω, 3 Ω, and 6 Ω respectively. For each voltage value, calculate the current in each branch using Ohm's law. Then, investigate the relationship between the branch resistance and the current through it. Find a general rule that describes how the total current divides among the branches in a parallel circuit. Justify your rule using Ohm's law and the fact that voltage is constant across parallel branches.

Solutions

34QuestionOhms Law V = IRAssessment Practice

6 marks~9 minCriterion C

A student investigates Ohm's law using a filament bulb, measuring current

I

for different applied voltages

V

. Results are recorded below.

V

(V): 1.0, 2.0, 3.0, 4.0, 5.0

I

(A): 0.20, 0.28, 0.34, 0.38, 0.41

a

Calculate the resistance

R

of the bulb at

V = 1.0

V and at

V = 5.0

V. [2]

b

Justify whether the filament bulb obeys Ohm's law, using values from the data. [2]

c

Evaluate the suitability of Ohm's law as a model for a filament bulb, discussing how resistance changes with voltage and the physical mechanism responsible. [2]

Solutions

35QuestionOhms Law V = IRAssessment Practice

4 marks~6 minCriterion A

A hospital monitoring system uses a 12 V battery to power two parallel sensor resistors:

R_1 = 4\ \Omega

and

R_2 = 6\ \Omega

.

a

Calculate the total resistance of the parallel combination. [2]

b

Deduce the total current drawn from the battery, and explain why a parallel arrangement — rather than series — ensures each sensor receives the full 12 V supply voltage. [2]

Solutions

36QuestionOhms Law V = IRAssessment Practice

4 marks~6 minCriterion B

A resistor in a circuit carries a current of

2 \text{ A}

and has a resistance of

6 \text{ Ω}

.

a

Deduce the voltage across the resistor using

V = IR

. [1]

b

The current increases to

5 \text{ A}

while resistance remains constant. Calculate the new voltage and justify why the voltage changed by the factor it did, with reference to

V = IR

. [2]

c

A second resistor is connected in series, doubling the total resistance. The current returns to

2 \text{ A}

. Analyse how the total voltage across the circuit compares to your answer in (a), explaining what this reveals about the relationship between resistance and voltage. [1]

Solutions

Electricity and Magnetism — Free MYP5 Physics Practice Questions