Physics — Mixed Practice — Part 1: 40 MCQs with Explanations
40 intermediate physics — mixed practice MCQs with answers and explanations for MDCAT, FSc, PPSC preparation.
40
Questions
Intermediate
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4
Exams Covered
60
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Intermediate MDCAT FSc PPSC FPSC
Last updated: Oct 13, 2026
40
Total Practice MCQs
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Q1 of 40
In Young's double slit experiment, if the separation between slits is doubled, the fringe width will:
Correct Answer: Option B — Become half
Detailed Academic Explanation:
Fringe width β = λD/d, where d is slit separation. If d is doubled, β becomes half.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q2 of 40
The magnitude of resultant of two vectors of magnitudes 3 N and 4 N cannot be:
Correct Answer: Option D — 8 N
Detailed Academic Explanation:
Maximum resultant = 3 + 4 = 7 N (when vectors are parallel). Minimum resultant = |4 - 3| = 1 N (when vectors are antiparallel). Resultant must be between 1 N and 7 N.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q3 of 40
In a simple pendulum, if the length is increased by 4 times, its time period becomes:
Correct Answer: Option A — Twice
Detailed Academic Explanation:
Time period T = 2π√(l/g). If l becomes 4l, T becomes 2π√(4l/g) = 2 × 2π√(l/g) = 2T.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q4 of 40
The electric field inside a uniformly charged spherical shell is:
Correct Answer: Option B — Zero
Detailed Academic Explanation:
By Gauss's law, electric field inside a uniformly charged spherical shell is zero everywhere.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q5 of 40
The binding energy per nucleon is maximum for:
Correct Answer: Option B — Iron-56
Detailed Academic Explanation:
Iron-56 has the highest binding energy per nucleon (~8.8 MeV), making it the most stable nucleus.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q6 of 40
The time period of a geostationary satellite is:
Correct Answer: Option B — 24 hours
Detailed Academic Explanation:
Geostationary satellites have orbital period equal to Earth's rotation period = 24 hours.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q7 of 40
The moment of inertia of a solid sphere about its diameter is:
Correct Answer: Option A — (2/5)MR²
Detailed Academic Explanation:
For solid sphere about diameter: I = (2/5)MR².
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q8 of 40
The resolving power of a microscope can be increased by:
Correct Answer: Option B — Decreasing wavelength
Detailed Academic Explanation:
Resolving power ∝ 1/λ. Smaller wavelength gives better resolution.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q9 of 40
A body is projected at an angle of 45° with horizontal. Its horizontal range is R. If projected at 30° with same speed, range will be:
Correct Answer: Option C — (√3/2)R
Detailed Academic Explanation:
Range R = u²sin2θ/g. For θ=45°, R₁ = u²/g. For θ=30°, R₂ = u²sin60°/g = (√3/2)u²/g = (√3/2)R.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q10 of 40
In a p-n junction diode under forward bias, the width of depletion region:
Correct Answer: Option B — Decreases
Detailed Academic Explanation:
Forward bias reduces the potential barrier, causing depletion region width to decrease.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q11 of 40
In Young's double slit experiment, the central fringe is:
Correct Answer: Option B — Always bright
Detailed Academic Explanation:
Central fringe (path difference = 0) is always bright for coherent sources.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q12 of 40
The Compton shift Δλ is given by:
Correct Answer: Option A — h/m₀c (1 - cosθ)
Detailed Academic Explanation:
Compton shift Δλ = λ' - λ = (h/m₀c)(1 - cosθ), where θ is scattering angle.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q13 of 40
The number of significant figures in 0.00450 is:
Correct Answer: Option B — 3
Detailed Academic Explanation:
Leading zeros are not significant. 0.00450 has 3 significant figures (4,5,0).
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q14 of 40
In a potentiometer experiment, the balancing length for a cell of emf 1.5 V is 300 cm. For another cell, balancing length is 450 cm. The emf of second cell is:
Correct Answer: Option C — 2.25 V
Detailed Academic Explanation:
E ∝ l. So E₂ = E₁ × (l₂/l₁) = 1.5 × (450/300) = 2.25 V.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q15 of 40
The angular speed of Earth about its own axis is approximately:
Correct Answer: Option A — 7.3 × 10^-5 rad/s
Detailed Academic Explanation:
ω = 2π/T = 2π/(24×3600) ≈ 7.27 × 10^-5 rad/s.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q16 of 40
The magnifying power of a simple microscope when image is formed at near point (D) is:
Correct Answer: Option A — 1 + D/f
Detailed Academic Explanation:
When image at near point (D = 25 cm), magnifying power M = 1 + D/f.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q17 of 40
The pressure at a depth h in a liquid of density ρ is:
The energy of electron in first excited state of hydrogen atom is:
Correct Answer: Option B — -3.4 eV
Detailed Academic Explanation:
E_n = -13.6/n² eV. For first excited state (n=2): E₂ = -13.6/4 = -3.4 eV.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q23 of 40
The self-inductance of a solenoid depends on:
Correct Answer: Option D — All of the above
Detailed Academic Explanation:
L = μ₀N²A/l depends on N (turns), A (area), and l (length).
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q24 of 40
The moment of inertia of a thin rod of mass M and length L about an axis through its center and perpendicular to its length is:
Correct Answer: Option C — ML²/12
Detailed Academic Explanation:
I = ML²/12 for axis through center perpendicular to rod.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q25 of 40
The wavelength of X-rays is of the order of:
Correct Answer: Option A — 10^-10 m
Detailed Academic Explanation:
X-ray wavelengths range from about 0.01 nm to 10 nm (10^-11 to 10^-8 m), typically ~10^-10 m.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q26 of 40
The binding energy of deuteron (²H) is about 2.2 MeV. Its mass defect is approximately:
Correct Answer: Option A — 0.0024 u
Detailed Academic Explanation:
Δm = E/c² = 2.2 MeV/(931.5 MeV/u) ≈ 0.00236 u ≈ 0.0024 u.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q27 of 40
The number of neutrons in ²³⁸U is:
Correct Answer: Option B — 146
Detailed Academic Explanation:
Number of neutrons N = A - Z = 238 - 92 = 146.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q28 of 40
The moment of inertia of a solid sphere of mass M and radius R about its diameter is:
Correct Answer: Option C — (2/5)MR²
Detailed Academic Explanation:
Moment of inertia of solid sphere about diameter: I = (2/5)MR². For hollow sphere: (2/3)MR²; for solid cylinder about axis: (1/2)MR².
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q29 of 40
The time taken by a freely falling body to cover first meter is t₁ and to cover second meter is t₂. Then:
Correct Answer: Option C — t₁ < t₂
Detailed Academic Explanation:
For free fall from rest: s = ½gt². Time to fall 1 m: t₁ = √(2/g). Time to fall 2 m: t_total = √(4/g) = √2·√(2/g). Time for second meter: t₂ = t_total - t₁ = √2·t₁ - t₁ = (√2-1)t₁ ≈ 0.414t₁. So t₁ > t₂.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q30 of 40
The efficiency of a transformer is maximum when:
Correct Answer: Option A — Copper losses = iron losses
Detailed Academic Explanation:
Maximum efficiency occurs when variable losses (copper losses ∝ I²) equal constant losses (iron losses).
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q31 of 40
The self-inductance of a coil depends on:
Correct Answer: Option D — All of the above
Detailed Academic Explanation:
Self-inductance L = μ₀μᵣN²A/l, where N is number of turns, A is area, l is length, and μᵣ is relative permeability of core material.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q32 of 40
The principle of superposition is applicable to:
Correct Answer: Option B — Linear systems only
Detailed Academic Explanation:
Superposition principle holds only for linear systems where the net response is the sum of responses to individual stimuli.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q33 of 40
The Brewster's angle for air-glass interface (n = 1.5) is approximately:
Correct Answer: Option C — 57°
Detailed Academic Explanation:
tan θ_B = n = 1.5. θ_B = tan⁻¹(1.5) ≈ 56.3° ≈ 57°.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q34 of 40
The coefficient of linear expansion α and coefficient of volume expansion γ are related as:
Correct Answer: Option C — γ = 3α
Detailed Academic Explanation:
For isotropic solids: γ ≈ 3α (exactly true for small expansions).
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q35 of 40
The energy of an electron in the nth orbit of hydrogen atom is proportional to:
Correct Answer: Option D — 1/n²
Detailed Academic Explanation:
Energy En = -13.6/n² eV for hydrogen. So |En| ∝ 1/n².
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q36 of 40
The moment of inertia depends on:
Correct Answer: Option C — Both mass distribution and axis of rotation
Detailed Academic Explanation:
Moment of inertia I = Σmr² depends on mass distribution relative to the axis of rotation. Same object has different I for different axes.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q37 of 40
The adiabatic index γ for monatomic gas is:
Correct Answer: Option C — 1.67
Detailed Academic Explanation:
For monatomic gases: degrees of freedom f = 3 (translational only). γ = 1 + 2/f = 1 + 2/3 = 5/3 ≈ 1.67.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q38 of 40
The binding energy of deuteron (²H) is approximately:
Correct Answer: Option A — 2.2 MeV
Detailed Academic Explanation:
Deuteron (proton+neutron) has binding energy of 2.224 MeV, relatively low compared to heavier nuclei.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q39 of 40
The time period of geostationary satellite is:
Correct Answer: Option A — 24 hours
Detailed Academic Explanation:
Geostationary satellites orbit in equatorial plane with period equal to Earth's rotational period (24 hours), appearing stationary relative to ground.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
Q40 of 40
The energy of hydrogen atom in ground state is:
Correct Answer: Option B — -13.6 eV
Detailed Academic Explanation:
Ground state (n=1) energy of hydrogen atom is -13.6 eV. Negative sign indicates bound state.
💡 Key Conceptual Anchor:
Physics — Mixed Practice
💡 How to Use These MCQs
Self-Assessment: Test your current knowledge level before studying.
Learning Aid: Read explanations carefully to understand concepts, not just memorize answers.
Revision Tool: Review these questions periodically before exams.
Time Management: Practice answering within time limits to improve speed.