IB DP Physics Mock Exam HL Paper 1A Set 5 - 2025 Syllabus

IB DP Physics Mock Exam HL Paper 1A Set 5

Prepare for the IB DP Physics Mock Exam HL Paper 1A Set 5 with our comprehensive mock exam set 5. Test your knowledge and understanding of key concepts with challenging questions covering all essential topics. Identify areas for improvement and boost your confidence for the real exam

IB DP Physics Mock Tests -All Sets

Question

In two experiments, X and Y, the kinetic energies \(E_{k}\) of photoelectrons emitted from two different metal surfaces were measured when light was shone on them. The graph shows how \(E_{k}\) varies with the frequency \(f\) of the incident radiation for both surfaces. From the graph, it can be concluded that in experiment Y…

(A) the surface has a smaller work function than the surface in experiment X.
(B) the surface has a larger work function than the surface in experiment X.
(C) the intensity of the incident light is less than in experiment X.
(D) the intensity of the incident light is more than in experiment X.

▶️ Answer/Explanation

Detailed solution

1. Photoelectric Equation:
\(E_k = hf – \Phi\), where \(\Phi\) is the work function.
This is a linear equation \(y = mx + c\), where gradient is \(h\) and x-intercept is the threshold frequency \(f_0 = \Phi/h\).

2. Analyze Graph:
The line for Y has a larger x-intercept (threshold frequency) than X.
Since \(\Phi = h f_0\), a higher \(f_0\) means a larger work function.

3. Evaluate Options:
(A) Incorrect.
(B) Correct. Y has a larger work function.
(C) & (D) Intensity affects the number of electrons (current), not the kinetic energy or the threshold frequency. The graph tells us nothing about intensity.
✅ Answer: (B)

Question

Negative charges move counter-clockwise in a circular coil with uniform magnetic field into the page.

What is the magnetic effect?

(A) Coil rotates clockwise
(B) Coil rotates counter-clockwise
(C) Coil diameter increases
(D) Coil diameter decreases

▶️ Answer/Explanation

Detailed solution

Negative charges moving counter-clockwise = conventional current flows clockwise
Using right-hand rule for magnetic force on current loops:
• Field into page
• Current clockwise
This creates an outward magnetic force on all parts of the loop, tending to expand it
✅ Answer: (C) The diameter of the coil will tend to increase

Question

A suitable material for use as a moderator in a nuclear reactor is…

(A) cadmium
(B) concrete
(C) uranium-238
(D) water

▶️ Answer/Explanation

Detailed solution

A moderator slows down fast neutrons to thermal energies to sustain fission.
Good moderators have light nuclei that can slow neutrons through elastic collisions.
• Cadmium: neutron absorber (control rods)
• Concrete: shielding material
• Uranium-238: fissionable material
• Water: contains hydrogen, excellent moderator
✅ Answer: (D) water

IB DP Physics Mock Exam HL Paper 1A Set 5 - 2025 Syllabus