List of top Physics Questions

Two charged particles P and Q, having the same charge but different masses \( m_p \) and \( m_Q \), start from rest and travel equal distances in a uniform electric field \( \vec{E} \) in time \( t_p \) and \( t_Q \) respectively. Neglecting the effect of gravity, the ratio \( \frac{t_p}{t_Q} \) is:
A beam of light consisting of a known wavelength 520 nm and an unknown wavelength λ, used in Young’s double-slit experiment, produces two interference patterns such that the fourth bright fringe of unknown wavelength coincides with the fifth bright fringe of known wavelength. Find the value of λ.
Define coherent sources. Can two independent sodium lamps be coherent?
State Huygens' principle. Plane wave incident at angle i on reflecting surface. Construct reflected wavefront and prove i=r.
The refractive index of the material of a prism is √2. If the refracting angle of the prism is 60◦, find:
(1) Angle of minimum deviation:
(2) Angle of incidence:
A ray of light is incident normally on a refracting face of a prism of prism angle A and suffers a deviation of angle δ. Prove that the refractive index n of the material of the prism is given by:n = sin(A+δ)/sin A
A ray of light passes through a triangular prism. Show graphically how the angle of deviation varies with the angle of incidence. Hence define the angle of minimum deviation
(i) Draw a step-up transformer diagram. Describe its working principle. Explain 3 energy loss causes.
(ii) Does a step-up transformer violate energy conservation? Explain.
(iii) A step-up transformer (N_p=200, N_s=3000) has V_p=90V, I_s=2A. Calculate V_s and I_p.
(i) Derive the impedance of an R-C series circuit connected to an AC source v = v_m sin(ωt).
(ii) When does an inductor act as a conductor? Explain.
(iii) A lamp (R) and inductor (L) in series with 220V-50Hz AC give 11A. With 110V DC, it gives 11A. Find L.
(a) "EM wavelength correlates with the size of the radiating system." Give two examples.
(i) Why do long-distance radio broadcasts use shortwave bands?
(ii) Why are X-ray telescopes satellite-based, while optical/radio telescopes are ground-based?
(a) State Bohr's postulates for the hydrogen atom.
(b) A hydrogen atom de-excites from level n to (n-1). Show that emitted frequency ν ∝ α/n³ for large n (α = constant).
An air-filled parallel plate capacitor (d = 1mm, C = 20pF) is charged to 4.0µC. Find work done to increase plate separation to 5mm (constant charge).
Differentiate between diffusion and drift current. Explain their role in p-n junction formation.
Who first produced and observed EM waves in the 25mm-5mm range?
A transformer has 500 primary turns and 5000 secondary turns. Input is 220V-50Hz. What's the output?
(a) Two characteristic properties of nuclear force. (b) Plot potential energy of a nucleon pair vs. separation. Two conclusions from the plot.
Coils P and Q. Current in P induces current in Q. (a) Explain the phenomenon. (b) Two factors affecting current in Q. (c) Direction of current in Q when current is in P and (i) R increases, (ii) R decreases.
A bar magnet (2.5 J/T) is aligned with a 0.32 T field. (a) Find work done to align it (i) normal, (ii) opposite to the field. (b) Find torque in both cases.
(a) Define current density. Scalar or vector? E field in a conductor (n electrons/volume, mass m, charge -e, relaxation time τ). Show j = αE, where α = ne²/mτ. (b) What's a Wheatstone bridge? Balance conditions?
Charges Q1, Q2, and Q3 are at (-d,0), (0,0), and (d,0). Q1=Q3, Q2>0. Find the nature and value of Q1 for zero potential energy.
How does conductivity of an intrinsic semiconductor vary with temperature? Show in a plot.
An object is placed 30 cm in front of a concave mirror (radius of curvature 40 cm). Find: (i) image position (ii) magnification
Two batteries (6V, 0.8Ω and 3V, 0.2Ω) are connected in series with external resistance R. Find R so that the potential difference across the 6V battery is zero.
An electron and a proton have the same wavelength λ. This implies they have the same:
Two beams (3.3 eV and 11.3 eV) illuminate a metal (work function 2.3 eV). Find the ratio of maximum electron speeds.