These essential MCQ questions are selected from the most important topics in CBSE Class 12 Physics Board Examination 2026. Sections include Electrostatics, Current Electricity, Magnetic Effects, Electromagnetic Induction, Optics and Modern Physics as per NCERT syllabus. For truely unlimited daily MCQ practice, visit Vooo AI Education.
⚡ CBSE Class 12 Physics
1SI unit of electric charge is:
Answer: C — Coulomb
The SI unit of electric charge is the Coulomb (C), named after French physicist Charles-Augustin de Coulomb. One coulomb is the charge transported by a current of one ampere in one second (1 C = 1 A·s).
The SI unit of electric charge is the Coulomb (C), named after French physicist Charles-Augustin de Coulomb. One coulomb is the charge transported by a current of one ampere in one second (1 C = 1 A·s).
2Which law gives force between two charges?
Answer: B — Coulomb's Law
Coulomb's Law states that the electrostatic force between two point charges is directly proportional to the product of charges and inversely proportional to the square of distance between them: F = kq₁q₂/r².
Coulomb's Law states that the electrostatic force between two point charges is directly proportional to the product of charges and inversely proportional to the square of distance between them: F = kq₁q₂/r².
3The focal length of a concave mirror is:
Answer: B — Negative
In the standard sign convention, the focal length of a concave mirror is negative (focal point is in front of the mirror). Convex mirrors have positive focal length. This convention: distances measured in direction of incident light are positive.
In the standard sign convention, the focal length of a concave mirror is negative (focal point is in front of the mirror). Convex mirrors have positive focal length. This convention: distances measured in direction of incident light are positive.
4Einstein's photoelectric equation is:
Answer: B — KE = hν − φ
Einstein's photoelectric equation: Maximum Kinetic Energy = hν − φ, where h is Planck's constant, ν is frequency of incident light and φ (phi) is the work function of the metal. This explained the photoelectric effect for which Einstein won the 1921 Nobel Prize.
Einstein's photoelectric equation: Maximum Kinetic Energy = hν − φ, where h is Planck's constant, ν is frequency of incident light and φ (phi) is the work function of the metal. This explained the photoelectric effect for which Einstein won the 1921 Nobel Prize.
5Magnetic field lines inside a solenoid are:
Answer: D — Parallel and uniform
Inside a solenoid (a coil of wire carrying current), the magnetic field lines are parallel, uniform and directed along the axis. This uniform field is similar to that inside a bar magnet. The field outside a solenoid is very weak.
Inside a solenoid (a coil of wire carrying current), the magnetic field lines are parallel, uniform and directed along the axis. This uniform field is similar to that inside a bar magnet. The field outside a solenoid is very weak.
6Which phenomenon proves the wave nature of light?
Answer: C — Interference
Interference (and diffraction) proves the wave nature of light. The photoelectric effect and Compton effect prove the particle (photon) nature of light. This dual nature — wave and particle — is called wave-particle duality.
Interference (and diffraction) proves the wave nature of light. The photoelectric effect and Compton effect prove the particle (photon) nature of light. This dual nature — wave and particle — is called wave-particle duality.
7In a p-n junction diode, forward bias means:
Answer: B — p-side to positive terminal
In forward bias, the p-side of the diode is connected to the positive terminal and n-side to the negative terminal of the battery. This reduces the depletion layer and allows current to flow. In reverse bias, the diode blocks current.
In forward bias, the p-side of the diode is connected to the positive terminal and n-side to the negative terminal of the battery. This reduces the depletion layer and allows current to flow. In reverse bias, the diode blocks current.
8The unit of magnetic flux is:
Answer: B — Weber
The SI unit of magnetic flux (Φ) is the Weber (Wb), named after German physicist Wilhelm Eduard Weber. 1 Weber = 1 Tesla × 1 metre². The SI unit of magnetic field (flux density) is the Tesla (T).
The SI unit of magnetic flux (Φ) is the Weber (Wb), named after German physicist Wilhelm Eduard Weber. 1 Weber = 1 Tesla × 1 metre². The SI unit of magnetic field (flux density) is the Tesla (T).
9Refractive index of glass with respect to air is 1.5. Speed of light in glass?
Answer: B — 2×10⁸ m/s
Refractive index (n) = Speed of light in vacuum (c) / Speed of light in medium (v). So v = c/n = 3×10⁸/1.5 = 2×10⁸ m/s. Light slows down when entering a denser medium — this causes refraction (bending of light).
Refractive index (n) = Speed of light in vacuum (c) / Speed of light in medium (v). So v = c/n = 3×10⁸/1.5 = 2×10⁸ m/s. Light slows down when entering a denser medium — this causes refraction (bending of light).
10De Broglie wavelength is associated with:
Answer: C — All moving particles
De Broglie proposed that all moving particles (not just photons) have an associated wavelength: λ = h/mv, where h is Planck's constant, m is mass and v is velocity. This wave nature of matter was experimentally confirmed by electron diffraction.
De Broglie proposed that all moving particles (not just photons) have an associated wavelength: λ = h/mv, where h is Planck's constant, m is mass and v is velocity. This wave nature of matter was experimentally confirmed by electron diffraction.
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