IB MYP Sciences – Electromagnetism and waves Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – the IB holds copyright in its own papers. Use these alongside the official past papers available through your school or the IB store.

This practice set covers electromagnetism and waves for IB MYP Sciences. It is aligned to the International Baccalaureate Organization, Middle Years Programme Subject Brief – Sciences, from 2014, which lists “electromagnetism” and “waves” among the topics explored in the MYP sciences on-screen examinations. MYP has no SL/HL split, and the set suits MYP years 4 and 5, including students preparing for the on-screen examination at the end of year 5.

MYP has no prescribed content list: schools design their own units, so check your unit’s scope with your teacher. Each question is labelled with the criterion it trains. Real MYP work is judged against criterion level descriptors (1–8), so the [1] points here are a revision aid, not IB marks.

Learn the content first in the study guide. For questions 9 to 11, see investigation skills exam preparation.

Take EM waves to travel at 3.0 × 10⁸ m/s.

Questions

1. (Criterion A) Here is a list of materials: copper, nickel, aluminium, steel, cobalt, brass.

(a) Write down the three magnetic materials. [2] (b) State what happens when the north poles of two bar magnets are brought close together. [1]

2. (Criterion A) A student makes an electromagnet by winding insulated wire around an iron nail.

(a) State three changes that would make the electromagnet stronger. [3] (b) Explain why a soft iron core is chosen for a scrapyard crane rather than a steel one. [1]

3. (Criterion A) A copper wire sits at right angles between the poles of a horseshoe magnet. When the current is switched on, the wire jumps upwards.

(a) Predict what the wire does if the current is reversed. [1] (b) Predict what the wire does if both the current and the magnetic field are reversed. [1] (c) State one change that would make the force on the wire larger. [1]

4. (Criterion A) A bar magnet is pushed into a coil connected to a sensitive meter. The needle flicks to the right.

(a) State what the needle shows while the magnet is held still inside the coil. [1] (b) State what the needle does when the magnet is pulled out. [1] (c) State the effect of pushing the magnet in faster. [1] (d) Name the device that uses this effect to transform kinetic energy into electrical energy. [1]

5. (Criterion A)

(a) Describe the difference between a transverse and a longitudinal wave. [2] (b) Give one example of each type. [2]

6. (Criterion A, calculator allowed)

(a) A radio station broadcasts at 100 MHz. Calculate the wavelength. [2] (b) A microwave oven uses a frequency of 2.45 GHz. Calculate the wavelength in cm, to 3 significant figures. [2]

7. (Criterion A, calculator allowed) In a ripple tank, straight water waves of frequency 1.5 Hz travel at 0.30 m/s in deep water. They cross, at an angle, into a shallow region where they travel at 0.18 m/s.

(a) Calculate the wavelength in the deep water. [2] (b) Calculate the wavelength in the shallow water. [1] (c) Explain why the waves change direction at the boundary. [2]

8. (Criterion A) Radio waves, gamma rays, infrared, visible light, X-rays, ultraviolet and microwaves.

(a) Write these in order of increasing frequency. [2] (b) Give one use of infrared and one use of gamma rays. [2] (c) State one property shared by all electromagnetic waves. [1]

9. (Criterion B) Plan an investigation into how the number of turns of wire on an electromagnet affects its strength. You have a power supply, an ammeter, insulated wire, an iron core and a box of identical steel paperclips.

(a) Write a hypothesis with a scientific reason. [2] (b) Identify the independent variable, the dependent variable and two control variables. [3] (c) Outline a method, including the range of values and repeats. [2] (d) State one safety precaution. [1]

10. (Criterion C, calculator allowed) A student sets a ripple tank dipper to 5.0 Hz and measures the wavelength at different water depths. The data are fictional.

Depth / cm	Wavelength / cm	Wave speed / m/s
1.0	6.3	0.315
2.0	8.9
3.0	10.8	0.540
4.0	10.1	0.505
5.0	14.0

(a) Complete the two missing wave speeds. [2] (b) Identify the anomalous result and suggest a cause. [2] (c) Describe the trend in the data. [1] (d) The student’s hypothesis was “wave speed is directly proportional to depth”. Evaluate this hypothesis using the data. [2] (e) Suggest one improvement to the method. [1]

11. (Criterion C, calculator allowed) A ship measures sea depth by sonar. Sound travels at 1500 m/s in seawater. Three echo times are recorded: 0.48 s, 0.52 s and 0.50 s.

(a) Calculate the mean echo time. [1] (b) Calculate the depth of the seabed. [2] (c) Calculate the echo time expected where the sea is 600 m deep. [1] (d) Suggest one reason why the three times differ. [1]

12. (Criterion D, extended response) A hospital in the fictional town of Kellbridge can buy either an X-ray machine or an ultrasound scanner. Evaluate X-rays and ultrasound for medical imaging: explain how each works, give benefits and limitations, and reach a justified judgement. [10]

Answers

1. (a) Nickel and steel [1]; cobalt, with no non-magnetic material listed [1]. (b) They repel (push apart) [1]. Examiner insight: A list with an extra wrong material such as brass loses the second point; only name what the question asks for.

2. (a) Increase the current [1]; increase the number of turns [1]; use a soft iron core rather than no core (or a thicker iron core) [1]. (b) Soft iron loses its magnetism when the current is switched off, so the crane can release its load; steel would stay magnetised [1]. Examiner insight: “Use a bigger magnet” earns nothing; each point must name a variable of the electromagnet itself.

3. (a) It moves downwards [1]. (b) It still moves upwards, because two reversals cancel [1]. (c) Increase the current, or use a stronger magnet [1]. Examiner insight: Predictions must state a direction; “it moves the other way” is accepted, “it moves” is not.

4. (a) Zero, because nothing is moving so no voltage is induced [1]. (b) It flicks to the left (the opposite direction) [1]. (c) A larger deflection [1]. (d) A generator (dynamo) [1]. Examiner insight: In (a), add the reason “no relative movement”; a bare “zero” can look like a guess.

5. (a) Transverse: vibrations at right angles to the direction of energy transfer [1]. Longitudinal: vibrations parallel to the direction of energy transfer [1]. (b) Transverse: light, any EM wave, or water waves [1]. Longitudinal: sound [1]. Examiner insight: Refer to the direction of energy transfer, not just “the direction of the wave”, to earn both description points.

6. (a) λ = v/f = (3.0 × 10⁸)/(100 × 10⁶) [1] = 3.0 m [1]. (b) λ = (3.0 × 10⁸)/(2.45 × 10⁹) = 0.1224… m [1] = 12.2 cm [1]. Examiner insight: The accuracy point in (b) needs both the conversion to cm and 3 significant figures; 0.122 m alone answers a different question.

7. (a) λ = v/f = 0.30/1.5 [1] = 0.20 m [1]. (b) λ = 0.18/1.5 = 0.12 m [1]. (c) The waves slow down in the shallow water [1]; the part of each wavefront that reaches the shallow region first slows first, so the waves bend towards the normal [1]. Examiner insight: Frequency is unchanged at the boundary; recalculating a new frequency loses the (b) point.

8. (a) Radio, microwaves, infrared in that order [1]; then visible, ultraviolet, X-rays, gamma [1]. (b) Infrared: remote controls, thermal imaging or grills [1]. Gamma: killing cancer cells or sterilising medical equipment [1]. (c) Any one: transverse; travel through a vacuum; travel at 3.0 × 10⁸ m/s in a vacuum; transfer energy [1]. Examiner insight: Increasing frequency and increasing wavelength are opposite orders; a reversed list earns nothing.

9. (a) More turns will make the electromagnet pick up more paperclips [1], because each turn adds its own magnetic field to the total [1]. (b) Independent: number of turns [1]. Dependent: number of paperclips lifted [1]. Controls, any two: current (checked on the ammeter), same core, same paperclips [1]. (c) Test five values, such as 10, 20, 30, 40 and 50 turns [1]; repeat each three times and find the mean [1]. (d) Keep the current low and switch off between readings, because the wire gets hot [1]. Examiner insight: A control variable counts only if it could really change the result; “same room” earns nothing.

10. (a) v = fλ = 5.0 × 0.089 = 0.445 m/s [1]; 5.0 × 0.140 = 0.700 m/s [1]. (b) The 4.0 cm reading (0.505 m/s) is anomalous: it is lower than the 3.0 cm speed [1]; possible cause: uneven depth or a wavelength misread from a blurred image [1]. (c) As depth increases, wave speed increases [1]. (d) Doubling the depth from 1.0 to 2.0 cm raises the speed from 0.315 to 0.445 m/s, not double [1]; so speed rises with depth but is not proportional to it, and the hypothesis is not supported [1]. (e) Measure across several waves (for example ten) and divide, or photograph the waves against a ruler [1]. Examiner insight: Evaluating a hypothesis needs numbers quoted from the table, not just “the graph is curved”.

11. (a) (0.48 + 0.52 + 0.50)/3 = 0.50 s [1]. (b) Distance travelled = 1500 × 0.50 = 750 m [1]; depth = 750/2 = 375 m [1]. (c) t = 2 × 600/1500 = 0.80 s [1]. (d) The ship is moving over an uneven seabed, or the timing of the echo is imprecise [1]. Examiner insight: Forgetting the “there and back” halving in (b) loses the accuracy point but keeps the method point for 1500 × 0.50.

12. Indicative points: X-rays are high-frequency EM waves that pass through soft tissue but are absorbed by bone [1]. So an X-ray image is quick and shows fractures clearly [1]. X-rays are ionising: they can damage cells and raise cancer risk [1]. The risk is cut by a low dose, lead aprons and staff behind a screen [1]. Ultrasound is a longitudinal sound wave above the range of human hearing [1]. It reflects at boundaries between tissues; echo times build the image [1]. Ultrasound is not ionising, so it is used for pregnancy scans [1]. It images bone poorly and does not pass well through air, as in the lungs [1]. Judgement: the choice depends on the body part and patient; X-rays suit fractures, ultrasound suits soft tissue [1]. A further justified point, such as cost, demand for each scan, or radiation exposure for patients needing repeat scans [1]. Examiner insight: Criterion D rewards balance; a one-sided answer, however detailed, cannot reach the top band.

Where marks are usually lost

• Naming steel as the best electromagnet core. Soft iron is correct because it demagnetises.
• Saying a stationary magnet in a coil induces a current.
• Not converting MHz and GHz to Hz before using v = fλ.
• Missing the halving step in echo and sonar calculations.
• Saying frequency changes on refraction.
• Listing the EM spectrum in the wrong direction for the question.
• Hypotheses with no scientific reason, or control variables that could not affect the result.
• Criterion D answers that describe one technology only, with no judgement.

Next steps

• Electromagnetism and waves revision notes
• Electromagnetism and waves study guide
• IB MYP Sciences course hub
• Printable IB MYP Sciences checklist
• All free 10-minute diagnostics
• Book a free trial class

Official syllabus

International Baccalaureate Organization, Middle Years Programme Subject Brief – Sciences, from 2014.