IB Physics Paper 1

The change in the IB Physics syllabus (2025) may leave many students confused about the new format of Paper 1. In this post, however, we’ll break down everything you need to know, so you can approach the exam with clarity and confidence.

IB Physics Paper 1

• Accounts for 36% of the student's subject grade (SL & HL).
• SL students have 1 hour 30 minutes, while HL students are given 2 hours to complete Paper 1.
• Calculators are permitted.
• Paper 1 is made up of two separate booklets – Paper 1A and Paper 1B. Both papers are however completed in one sitting.

Paper 1A 

• Solely made up of multiple-choice questions – students must select one answer from the four provided. 

   

• Each question is worth 1 mark.

   

• The SL Paper 1A consists of 30 multiple choice-questions (30 marks total), while the HL Paper 1A consists of 40 multiple-choice questions (40 marks).

   

• Points are not deducted for incorrect answers.

A typical Section A SL question may look the following way:

A car has an initial speed of 16 m s^-1. It decelerates at 4.0 m s^-2 until it stops. What is the distance travelled by the car? 

A. 4m 

B. 16m 

C. 32m 

D. 64m 

A typical Section A HL question may look the following way:

Monochromatic light of frequency f₁ is incident on the surface of a metal. The stopping voltage for this light is V₁. When the frequency of the radiation is changed to f₂, the stopping voltage is V₂. What is the quantity V₂-V₁/f₁-f₂ equal to?

A. h

B. h/e

C. h/c

D. hc/e

Paper 1B

• Made up of data-based questions. 

• Questions relate to experimental work.

• The SL Paper 1B consists of 25 marks while the HL paper is marked out of 35.

   

• Points are not deducted for incorrect answers.

In Section B, students are presented with data-based questions. A typical SL Section B may look the following way:

A group of students investigate the motion of a conducting ball suspended from a long string. The ball is between two vertical metal plates that have an electric potential difference V between them. The ball is touched to one plate so that it becomes electrically charged and is repelled from the plate. For a given potential difference, the ball bounces between the plates with a constant period.

(a) The students vary V and measure the time T for the ball to move once from one plate to the other. The table shows some of the data.

(i) V is provided by two identical power supplies connected in series. The potential difference of each of the power supplies is known with an uncertainty of 0.01 kV. State the uncertainty in the potential difference V. [1]

(ii) T is measured with an electronic stopwatch that measures to the nearest 0.1 s. Describe how an uncertainty in T of less than 0.1 s can be achieved using this stopwatch. [2]

(iii) Outline why it is unlikely that the relationship between T and V is linear. [1]

(iv) Calculate the largest fractional uncertainty in T for these data. [2]

(b) The students suggest the following theoretical relationship between T and V :

T = A/V

where A is a constant. To verify the relationship, the variation of T with V1 is plotted:

(i) Determine A by drawing a line of best fit. [3]

(ii) State the units of A. [1]

(iii) The theoretical relationship assumes that the ball is only affected by the electric force. Suggest why, in order to test the relationship, the length of the string should be much greater than the distance between the plates. [2] 

In Section B, students are presented with data-based questions. A typical HL Section B may look the following way:

A group of students investigate the bending of a plastic ruler that is clamped horizontally at one end. A weight W attached to the other end causes the ruler to bend. The weight is contained in a scale pan. The students fix the length L of the ruler and vary W. For each value of W, the group measures the deflection d of the end of the ruler to which the weight is attached.

(a) The group obtains the following repeated readings for d for one value of W.

The group divides into two subgroups, A and B, to analyse the data. 

Group A quotes the mean value of d as 2.93 cm. 

Group B quotes the mean value of d as 2.8 cm. 

Discuss the values that the groups have quoted. [2]

(b) The variation of d with W is shown.

Outline one experimental reason why the graph does not go through the origin. [1]

(c) Theory predicts that d ∝ W^xL^y/EI 

where E and I are constants. The fundamental units of I are m⁴ and those of E are kg m^-1 s^-2. Calculate x and y. [2]

(d) The ruler has cross-sectional area A = a × b, where a = (28 ± 1) mm and b = (3.00 ± 0.05)mm. 

(i) Suggest an appropriate measuring instrument for determining b. [1]

(ii) Calculate the percentage uncertainty in the value of A. [2]

How to succeed in Paper 1?

Section A

While multiple-choice questions may seem simple, many students find them unexpectedly difficult. The options are crafted to make more than one choice appear correct, even though only one is. Furthermore, with only 45 minutes for SL and 1 hour for HL (assuming equal time is allotted between Paper 1A and 1B), you have about a minute and a half per question, which adds to the pressure. However, you can master Paper 1A by regularly practicing sample questions and timing yourself. 

Section B

The key to excelling in Paper 1B is your ability to critically assess the experiments and data presented, while integrating relevant syllabus knowledge. The Physics Paper 1B requires not just an understanding of theoretical concepts but also the ability to interpret experimental work accurately. A thorough understanding of experimental work and analytical skills are therefore essential for this section. 

We hope you found this post helpful. For more useful materials associated with the IB check out the wide variety of IA, EE and TOK exemplars available at Clastify.