IGCSE Physics 1.1 Length and Time MCQs – 30 Practice Questions with Answers (Cambridge 0625)
Free practice questions for Cambridge IGCSE Physics 0625, Section 1.1 Length and Time, covering both Core and Supplement material. Every question has a worked explanation – tap “Show Answer” to check yourself.
Units, Prefixes & Measuring Length
Q1. What is the SI unit of length?
- (A) centimetre
- (B) metre
- (C) kilometre
- (D) millimetre
Show Answer
Answer: B – The metre (m) is the SI base unit of length. Centimetres, kilometres and millimetres are convenient multiples and sub-multiples, but the SI unit itself is the metre.
Q2. Which prefix means 10−6?
- (A) micro
- (B) milli
- (C) nano
- (D) centi
Show Answer
Answer: A – micro = 10−6. For comparison: milli = 10−3, centi = 10−2 and nano = 10−9.
Q3. A student runs 2.5 km. What is this distance in metres?
- (A) 25 m
- (B) 250 m
- (C) 2500 m
- (D) 25 000 m
Show Answer
Answer: C – 1 km = 1000 m, so 2.5 km = 2.5 × 1000 = 2500 m.
Q4. A hair has a thickness of 4500 µm (micrometres). What is this thickness in millimetres?
- (A) 0.45 mm
- (B) 45 mm
- (C) 450 mm
- (D) 4.5 mm
Show Answer
Answer: D – 4500 µm = 4500 × 10−6 m = 4.5 × 10−3 m = 4.5 mm. (1 mm = 1000 µm, so divide 4500 by 1000.)
Q5. A school ruler is graduated in millimetres. To what precision can a length be measured with this ruler?
- (A) 1 cm
- (B) 1 mm
- (C) 0.1 mm
- (D) 0.01 mm
Show Answer
Answer: B – An instrument can normally be read to its smallest division. The smallest division on the ruler is 1 mm, so lengths are measured to the nearest 1 mm (0.1 cm).
Q6. A vernier caliper has a least count of 0.01 cm. The main scale reads 1.6 cm and the 8th vernier division coincides with a main scale line. What is the measured length?
- (A) 1.60 cm
- (B) 1.08 cm
- (C) 1.68 cm
- (D) 2.40 cm
Show Answer
Answer: C – Length = main scale reading + (coinciding division × least count) = 1.6 + (8 × 0.01) = 1.6 + 0.08 = 1.68 cm.
Q7. A micrometer screw gauge (pitch 0.5 mm, 50 thimble divisions) is used to measure the diameter of a wire. The sleeve shows 4.5 mm and the thimble reads 37 divisions. What is the diameter?
- (A) 4.87 mm
- (B) 4.50 mm
- (C) 5.37 mm
- (D) 4.37 mm
Show Answer
Answer: A – Each thimble division = 0.5 mm / 50 = 0.01 mm. Diameter = 4.5 + (37 × 0.01) = 4.5 + 0.37 = 4.87 mm.
Q8. A micrometer screw gauge reads +0.04 mm when its jaws are fully closed (a positive zero error). It reads 3.92 mm when measuring the thickness of a metal sheet. What is the true thickness of the sheet?
- (A) 3.92 mm
- (B) 3.96 mm
- (C) 3.84 mm
- (D) 3.88 mm
Show Answer
Answer: D – A positive zero error must be subtracted: true thickness = 3.92 − 0.04 = 3.88 mm. Forgetting the zero error is the classic trap here.
Q9. The screw of a micrometer has a pitch of 0.5 mm and the thimble is divided into 50 equal divisions. What is the smallest length one thimble division represents?
- (A) 0.001 mm
- (B) 0.01 mm
- (C) 0.1 mm
- (D) 0.5 mm
Show Answer
Answer: B – One full turn advances the screw by one pitch (0.5 mm) over 50 divisions, so one division = 0.5 / 50 = 0.01 mm. This is why a micrometer is so precise.
Q10. A metal wire has a diameter of about 0.5 mm. Which instrument gives the most precise measurement of this diameter?
- (A) metre rule
- (B) measuring tape
- (C) micrometer screw gauge
- (D) vernier calipers
Show Answer
Answer: C – The micrometer reads to 0.01 mm, finer than vernier calipers (0.1 mm) and far finer than a rule or tape (1 mm), so it is the best choice for a thin wire.
Measuring Volumes & Density of Instruments
Q11. When reading the volume of water in a measuring cylinder, how should the reading be taken?
- (A) at eye level, using the bottom of the meniscus
- (B) from above, using the top of the meniscus
- (C) from below, using the top of the meniscus
- (D) at any angle, using the middle of the meniscus
Show Answer
Answer: A – The eye must be level with the surface and the reading taken at the bottom of the curved meniscus. Reading the top of the meniscus, or reading from above or below, gives a wrong value (parallax and meniscus errors).
Q12. In a measuring cylinder, the bottom of the meniscus is level with the 46 cm3 mark and the top edge of the meniscus is level with 47 cm3. What is the volume of the liquid?
- (A) 45 cm3
- (B) 47 cm3
- (C) 46 cm3
- (D) 48 cm3
Show Answer
Answer: C – Volumes in a measuring cylinder are always read at the bottom of the meniscus, so the volume is 46 cm3, not 47 cm3.
Q13. A rectangular metal block measures 4.0 cm × 3.0 cm × 2.0 cm. What is its volume?
- (A) 9.0 cm3
- (B) 24 cm3
- (C) 18 cm3
- (D) 12 cm3
Show Answer
Answer: B – Volume of a regular solid = length × width × height = 4.0 × 3.0 × 2.0 = 24 cm3. (Adding the sides, 9.0, is the trap.)
Q14. A measuring cylinder contains 35 cm3 of water. A stone is lowered into the water and the level rises to 52 cm3. What is the volume of the stone?
- (A) 35 cm3
- (B) 52 cm3
- (C) 87 cm3
- (D) 17 cm3
Show Answer
Answer: D – In the displacement method, the volume of the solid = final level − initial level = 52 − 35 = 17 cm3.
Q15. A large irregular rock cannot fit into a measuring cylinder. Which method correctly measures its volume?
- (A) weigh the rock and divide by 10
- (B) fill a displacement (eureka) can to its spout, immerse the rock, and collect and measure the overflow water
- (C) measure its length, width and height and multiply
- (D) float the rock in a tank and read the water level only
Show Answer
Answer: B – A displacement can is used for solids too big for a measuring cylinder: the volume of water that overflows when the rock is fully immersed equals the volume of the rock.
Q16. Which instrument measures the volume of a liquid with the greatest precision?
- (A) beaker
- (B) measuring cylinder
- (C) burette
- (D) conical flask
Show Answer
Answer: C – A burette has very fine graduations and can be read to about 0.05 cm3, making it more precise than a measuring cylinder. Beakers and flasks give only rough volumes.
Q17. A student wants to find the volume of a cork, which floats on water. What is the correct technique?
- (A) tie the cork to a heavy sinker, measure the volume of the sinker alone, then of sinker + cork together, and subtract
- (B) push the cork just under the surface with a finger and read the level
- (C) let the cork float and read how much of it is below the surface
- (D) soak the cork for an hour so that it sinks by itself
Show Answer
Answer: A – A sinker pulls the floating cork fully under the water. Volume of cork = (volume of sinker + cork) − (volume of sinker alone), both found by displacement.
Q18. A measuring cylinder holds 50 cm3 of water. A metal piece of mass 39 g is dropped in and the level rises to 55 cm3. What is the density of the metal?
- (A) 0.78 g/cm3
- (B) 78 g/cm3
- (C) 7.8 g/cm3
- (D) 3.9 g/cm3
Show Answer
Answer: C – Volume of the metal = 55 − 50 = 5 cm3. Density = mass / volume = 39 / 5 = 7.8 g/cm3. (Using the full 50 cm3 instead of the rise gives the 0.78 trap.)
Q19. What causes a parallax error when reading a scale, and how is it avoided?
- (A) a faulty zero on the scale; avoided by subtracting the zero error
- (B) the meniscus curving upwards; avoided by reading the top of the meniscus
- (C) the thickness of the glass; avoided by using a thinner cylinder
- (D) viewing the scale from an angle; avoided by placing the eye directly in line with (perpendicular to) the reading
Show Answer
Answer: D – Parallax error happens when the line of sight is at an angle to the scale. It is avoided by viewing the reading straight on, at eye level.
Q20. A student must measure about 8 cm3 of water as accurately as possible. Cylinders of capacity 10 cm3, 50 cm3 and 250 cm3 are available. Which should be used, and why?
- (A) the 10 cm3 cylinder, because its graduations are finest and the percentage error is smallest
- (B) the 250 cm3 cylinder, because it is the largest
- (C) the 50 cm3 cylinder, because it is in the middle
- (D) any of them, because cylinder size makes no difference
Show Answer
Answer: A – The smallest cylinder that can hold the volume has the finest divisions, so the same reading uncertainty is a much smaller percentage of 8 cm3.
Measuring Time & the Pendulum
Q21. A student uses a hand stopwatch. Because of human reaction time, the error in starting and stopping the watch is roughly
- (A) 0.002 s
- (B) 0.2 s
- (C) 2 s
- (D) 0.02 s
Show Answer
Answer: B – Human reaction time is about 0.2-0.3 s. This fixed error matters a lot for a single short interval, which is why short times are not timed one at a time.
Q22. Why is the time for 20 complete oscillations of a pendulum measured, instead of the time for one oscillation?
- (A) the pendulum swings faster after the first swing
- (B) the stopwatch only works after 20 s
- (C) the fixed reaction-time error is spread over 20 oscillations, so the percentage error in the period is much smaller
- (D) one oscillation is too slow to see clearly
Show Answer
Answer: C – The reaction-time error (about 0.2 s) is roughly the same whether you time 1 or 20 swings. Dividing the total time by 20 divides the error in the period by 20 as well.
Q23. A pendulum takes 30 s to complete 20 oscillations. What is its period?
- (A) 1.5 s
- (B) 0.67 s
- (C) 20 s
- (D) 600 s
Show Answer
Answer: A – Period T = total time / number of oscillations = 30 / 20 = 1.5 s.
Q24. A pendulum has a period of 0.80 s. What is its frequency?
- (A) 0.80 Hz
- (B) 1.6 Hz
- (C) 0.64 Hz
- (D) 1.25 Hz
Show Answer
Answer: D – f = 1 / T = 1 / 0.80 = 1.25 Hz.
Q25. The period of a simple pendulum (for small swings) depends on
- (A) the mass of the bob only
- (B) the length of the pendulum only
- (C) the amplitude of the swing only
- (D) the mass of the bob and the amplitude
Show Answer
Answer: B – For small-amplitude swings, the period depends only on the length of the pendulum (and on g). Changing the bob mass or the (small) amplitude does not change the period.
Q26. The string of a pendulum is made longer, keeping everything else the same. What happens to the period?
- (A) it decreases
- (B) it stays the same
- (C) it increases
- (D) it becomes zero
Show Answer
Answer: C – A longer pendulum swings more slowly, so each oscillation takes more time: the period increases.
Q27. The length of a pendulum is increased from 0.25 m to 1.0 m (four times longer). By what factor does the period change? [Supplement]
- (A) it doubles
- (B) it increases by a factor of 4
- (C) it increases by a factor of 16
- (D) it halves
Show Answer
Answer: A – The period is proportional to the square root of the length (T ∝ √l). Quadrupling l multiplies T by √4 = 2, so the period doubles.
Q28. Which procedure gives the most accurate value for the period of a pendulum?
- (A) time one oscillation once
- (B) time one oscillation and repeat it three times, then average
- (C) time 5 oscillations and divide by 5
- (D) time 20 oscillations and divide by 20
Show Answer
Answer: D – Timing more oscillations makes the reaction-time error a smaller fraction of the measured total, so dividing the time for 20 oscillations by 20 gives the most accurate period.
Q29. A pendulum completes 40 oscillations in 50 s. What is its frequency?
- (A) 1.25 Hz
- (B) 0.80 Hz
- (C) 2000 Hz
- (D) 0.50 Hz
Show Answer
Answer: B – Period T = 50 / 40 = 1.25 s, so f = 1 / T = 1 / 1.25 = 0.80 Hz. (1.25 is the period in seconds, not the frequency.)
Q30. A student investigates what affects the period of a pendulum. Which change does NOT affect the period?
- (A) using a heavier bob on the same string
- (B) shortening the string
- (C) taking the pendulum to the Moon, where g is smaller
- (D) lengthening the string
Show Answer
Answer: A – The mass of the bob does not affect the period. Changing the length changes the period, and a smaller g (on the Moon) makes the period longer.
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All questions are original practice questions written for QuaidianPoint – not Cambridge past-paper questions.