AQA A-LEVEL PHYSICS PAPER 1 (PDF) | 2026 QUESTIONS &
ANSWERS + RATIONALES | STUDY GUIDE | 100% CORRECT
1. Which of the following best describes the base unit of mass in the SI system?
A) Pound
B) Kilogram
C) Gram
D) Slug
Correct Answer: Kilogram
Rationale: The kilogram (kg) is the SI base unit of mass. The gram is a derived unit equal to one-
thousandth of a kilogram. The pound and slug belong to the imperial system, not the SI system.
Base units are foundational for all physical measurements.
2. What is the primary function of a micrometer screw gauge?
A) To measure large distances with low precision
B) To measure small thicknesses with high precision
C) To measure temperature changes
D) To measure electric current
Correct Answer: To measure small thicknesses with high precision
Rationale: A micrometer screw gauge is a precision instrument used to measure small
dimensions, such as the thickness of a wire or the diameter of a small sphere, to within 0.01 mm.
It uses a calibrated screw to provide accurate readings. It does not measure temperature or
current.
3. According to the SI system, which prefix represents a factor of 10⁻⁹?
A) Nano
B) Micro
C) Milli
D) Pico
Correct Answer: Nano
Rationale: The prefix nano (n) represents 10⁻⁹. Micro represents 10⁻⁶, milli represents 10⁻³, and
pico represents 10⁻¹². Correct use of prefixes is essential for expressing physical quantities
concisely and accurately.
4. Which of the following is a scalar quantity?
A) Velocity
B) Force
C) Energy
D) Acceleration
Correct Answer: Energy
,Rationale: Energy is a scalar quantity because it has magnitude only. Velocity, force, and
acceleration are vector quantities, requiring both magnitude and direction for complete
description. Distinguishing scalars from vectors is fundamental in mechanics.
5. A student measures the length of a pendulum as 0.85 m. Which type of error is most
likely if the metre rule is worn at the zero mark?
A) Random error
B) Systematic error
C) Parallax error
D) Zero error
Correct Answer: Systematic error
Rationale: A worn metre rule introduces a systematic error because the error is consistent across
all measurements. Random errors vary unpredictably, while zero errors occur when an
instrument does not read zero when it should. Systematic errors affect accuracy and can be
corrected by calibration.
6. What is the uncertainty in a measurement of 45.6 ± 0.2 cm expressed as a percentage?
A) 0.4%
B) 0.44%
C) 0.5%
D) 2.2%
Correct Answer: 0.44%
Rationale: Percentage uncertainty = (absolute uncertainty / measurement) × 100%. For 45.6 ± 0.2
cm, this is (0..6) × 100% = 0.4386%, which rounds to 0.44%. This calculation is essential
for evaluating the precision of experimental results.
7. Which of the following best describes a hadron?
A) A particle that experiences the strong nuclear force
B) A particle that does not experience the strong nuclear force
C) A particle that is always charged
D) A particle that has no mass
Correct Answer: A particle that experiences the strong nuclear force
Rationale: Hadrons are composite particles made of quarks that interact via the strong nuclear
force. Examples include protons, neutrons, and mesons. Leptons, such as electrons and neutrinos,
do not experience the strong force. Hadrons may be charged or neutral.
8. What is the quark composition of a proton?
A) uud
B) udd
C) uus
D) uds
, Correct Answer: uud
Rationale: A proton consists of two up quarks and one down quark (uud), giving a net charge of
+1e. A neutron is udd, with a net charge of zero. Understanding quark composition is
fundamental to particle physics and the classification of hadrons.
9. Which exchange particle is responsible for the weak nuclear force?
A) Photon
B) Gluon
C) W boson
D) Graviton
Correct Answer: W boson
Rationale: The weak nuclear force is mediated by W and Z bosons. The photon mediates the
electromagnetic force, the gluon mediates the strong force, and the graviton is hypothetical for
gravity. The weak force is responsible for beta decay.
10. What is the primary function of a particle accelerator in physics research?
A) To slow down particles for study
B) To accelerate particles to high energies for collision experiments
C) To store particles indefinitely
D) To cool particles to absolute zero
Correct Answer: To accelerate particles to high energies for collision experiments
Rationale: Particle accelerators accelerate charged particles to very high speeds and energies
before colliding them. These collisions create new particles and allow scientists to study
fundamental forces and matter. They are not used to slow or cool particles.
11. What is the definition of the photoelectric work function?
A) The minimum energy required to remove an electron from a metal surface
B) The maximum kinetic energy of an emitted electron
C) The energy of a photon
D) The current produced by photoelectrons
Correct Answer: The minimum energy required to remove an electron from a metal surface
Rationale: The work function (Φ) is the minimum energy needed for an electron to escape from
the surface of a particular metal. It is a property of the metal and determines the threshold
frequency for the photoelectric effect. It is not the photon energy or electron kinetic energy.
12. Which of the following best describes the de Broglie wavelength?
A) The wavelength associated with a moving particle, given by λ = h/p
B) The wavelength of light emitted by an atom
C) The wavelength of a stationary particle
D) The wavelength of a photon in a vacuum
Correct Answer: The wavelength associated with a moving particle, given by λ = h/p
ANSWERS + RATIONALES | STUDY GUIDE | 100% CORRECT
1. Which of the following best describes the base unit of mass in the SI system?
A) Pound
B) Kilogram
C) Gram
D) Slug
Correct Answer: Kilogram
Rationale: The kilogram (kg) is the SI base unit of mass. The gram is a derived unit equal to one-
thousandth of a kilogram. The pound and slug belong to the imperial system, not the SI system.
Base units are foundational for all physical measurements.
2. What is the primary function of a micrometer screw gauge?
A) To measure large distances with low precision
B) To measure small thicknesses with high precision
C) To measure temperature changes
D) To measure electric current
Correct Answer: To measure small thicknesses with high precision
Rationale: A micrometer screw gauge is a precision instrument used to measure small
dimensions, such as the thickness of a wire or the diameter of a small sphere, to within 0.01 mm.
It uses a calibrated screw to provide accurate readings. It does not measure temperature or
current.
3. According to the SI system, which prefix represents a factor of 10⁻⁹?
A) Nano
B) Micro
C) Milli
D) Pico
Correct Answer: Nano
Rationale: The prefix nano (n) represents 10⁻⁹. Micro represents 10⁻⁶, milli represents 10⁻³, and
pico represents 10⁻¹². Correct use of prefixes is essential for expressing physical quantities
concisely and accurately.
4. Which of the following is a scalar quantity?
A) Velocity
B) Force
C) Energy
D) Acceleration
Correct Answer: Energy
,Rationale: Energy is a scalar quantity because it has magnitude only. Velocity, force, and
acceleration are vector quantities, requiring both magnitude and direction for complete
description. Distinguishing scalars from vectors is fundamental in mechanics.
5. A student measures the length of a pendulum as 0.85 m. Which type of error is most
likely if the metre rule is worn at the zero mark?
A) Random error
B) Systematic error
C) Parallax error
D) Zero error
Correct Answer: Systematic error
Rationale: A worn metre rule introduces a systematic error because the error is consistent across
all measurements. Random errors vary unpredictably, while zero errors occur when an
instrument does not read zero when it should. Systematic errors affect accuracy and can be
corrected by calibration.
6. What is the uncertainty in a measurement of 45.6 ± 0.2 cm expressed as a percentage?
A) 0.4%
B) 0.44%
C) 0.5%
D) 2.2%
Correct Answer: 0.44%
Rationale: Percentage uncertainty = (absolute uncertainty / measurement) × 100%. For 45.6 ± 0.2
cm, this is (0..6) × 100% = 0.4386%, which rounds to 0.44%. This calculation is essential
for evaluating the precision of experimental results.
7. Which of the following best describes a hadron?
A) A particle that experiences the strong nuclear force
B) A particle that does not experience the strong nuclear force
C) A particle that is always charged
D) A particle that has no mass
Correct Answer: A particle that experiences the strong nuclear force
Rationale: Hadrons are composite particles made of quarks that interact via the strong nuclear
force. Examples include protons, neutrons, and mesons. Leptons, such as electrons and neutrinos,
do not experience the strong force. Hadrons may be charged or neutral.
8. What is the quark composition of a proton?
A) uud
B) udd
C) uus
D) uds
, Correct Answer: uud
Rationale: A proton consists of two up quarks and one down quark (uud), giving a net charge of
+1e. A neutron is udd, with a net charge of zero. Understanding quark composition is
fundamental to particle physics and the classification of hadrons.
9. Which exchange particle is responsible for the weak nuclear force?
A) Photon
B) Gluon
C) W boson
D) Graviton
Correct Answer: W boson
Rationale: The weak nuclear force is mediated by W and Z bosons. The photon mediates the
electromagnetic force, the gluon mediates the strong force, and the graviton is hypothetical for
gravity. The weak force is responsible for beta decay.
10. What is the primary function of a particle accelerator in physics research?
A) To slow down particles for study
B) To accelerate particles to high energies for collision experiments
C) To store particles indefinitely
D) To cool particles to absolute zero
Correct Answer: To accelerate particles to high energies for collision experiments
Rationale: Particle accelerators accelerate charged particles to very high speeds and energies
before colliding them. These collisions create new particles and allow scientists to study
fundamental forces and matter. They are not used to slow or cool particles.
11. What is the definition of the photoelectric work function?
A) The minimum energy required to remove an electron from a metal surface
B) The maximum kinetic energy of an emitted electron
C) The energy of a photon
D) The current produced by photoelectrons
Correct Answer: The minimum energy required to remove an electron from a metal surface
Rationale: The work function (Φ) is the minimum energy needed for an electron to escape from
the surface of a particular metal. It is a property of the metal and determines the threshold
frequency for the photoelectric effect. It is not the photon energy or electron kinetic energy.
12. Which of the following best describes the de Broglie wavelength?
A) The wavelength associated with a moving particle, given by λ = h/p
B) The wavelength of light emitted by an atom
C) The wavelength of a stationary particle
D) The wavelength of a photon in a vacuum
Correct Answer: The wavelength associated with a moving particle, given by λ = h/p
