12th Grade Physics, Chemistry, Biology Paper Scheme 2025

A student is analyzing a circuit with multiple resistors and a capacitor. If the frequency of the AC source is increased, how will the impedance of the capacitor change, and what effect will this have on the overall circuit current?

Monochromatic light passes through a diffraction grating. If the wavelength of the light is decreased, how does the spacing of the bright fringes on the screen change?

Two isotopes of the same element have different numbers of neutrons. How does this difference primarily affect their chemical and physical properties?

In a nuclear reactor, what is the primary function of a moderator, and what properties must it possess to perform this function effectively?

A positively charged particle is moving through a magnetic field. Under what condition will the magnetic force on the particle be zero?

A series LCR circuit is connected to an AC voltage source. At a particular frequency, the inductive reactance is greater than the capacitive reactance. What can be said about the phase relationship between the current and the voltage in the circuit?

When light travels from air into glass, which properties of the light wave change, and how?

What is the primary role of the ozone layer in Earth's atmosphere, and what type of electromagnetic radiation is most effectively blocked by it?

What is the significance of the depletion region in a p-n junction, and how is its width affected by forward and reverse biasing?

In a common emitter transistor amplifier, what is the effect of increasing the base resistance on the voltage gain and input impedance?

The wave nature of particles, like electrons, is described by the de Broglie wavelength. If the momentum of an electron is doubled, what happens to its de Broglie wavelength?

A radioactive sample has a half-life of 10 days. How long will it take for 75% of the sample to decay?

What is the significance of the Bohr model in understanding atomic spectra, and what are its key limitations?

A photon of a certain frequency is incident on a metal surface, but no photoelectrons are emitted. What change could be made to the incident light to potentially induce photoelectric emission?

A current-carrying wire is placed in a uniform magnetic field. Under what condition is the force on the wire maximized?

A step-up transformer increases the voltage from the primary coil to the secondary coil. Which of the following statements is true regarding the current and power in the two coils, assuming an ideal transformer?

Which of the following best describes an intrinsic semiconductor at absolute zero temperature?

What is the effect of increasing the temperature of a metallic conductor on its electrical resistance, and what microscopic phenomenon explains this behavior?

Which of the following is the correct relationship between magnetic susceptibility ($\chi_m$) and relative permeability ($\mu_r$)?

The electrical resistance of a semiconductor generally decreases with increasing temperature. What is the primary reason for this behavior?

What is the significance of the 'knee voltage' in the context of a p-n junction diode's I-V characteristic curve, and what happens to the diode's behavior beyond this voltage?

What is the effect of increasing the impurity doping concentration in a semiconductor on its Fermi level?

A pure inductor of 25 mH is connected to a 220V AC source. If the source frequency is 50 Hz, what is the inductive reactance of the circuit?

In a Young's double-slit experiment, the slit separation is 0.28 mm and the screen is 1.4 m away. If the distance between the central bright fringe and the fourth bright fringe is 1.2 cm, what is the wavelength of the light used?

What is the wave nature of electrons utilized in electron microscopes to achieve resolutions beyond those of optical microscopes?

A zinc oxide varistor is used to protect circuits from voltage surges. How does its resistance typically change when subjected to a high-voltage transient?

Iodine-131, a radioactive isotope, is used in medical treatments. If Iodine-131 has a half-life of approximately 8 days, what proportion of the original Iodine-131 will remain after 24 days?

Which of the following phenomena provides direct evidence for the wave nature of matter?

What is the approximate ratio of the nuclear density compared to the atomic density?

What is the function of the moderator in a nuclear reactor?

Why is it impossible to use a single optical lens to correct for both chromatic aberration and spherical aberration simultaneously ?

An astronomical refracting telescope has a large objective lens and a smaller eyepiece. Explain why it is essential to have a significantly larger, high-quality objective lens for astronomical observation?

When ultraviolet light is used for water purification, what is the primary mechanism by which it disinfects the water, and what is a major limitation of this method?

Semiconductors are often doped to modify their electrical properties. How does doping affect the energy band structure, and what is the key difference between n-type and p-type doping?

Light has dual nature of waveform and ray. Explain how both of them relate to one another for a normal person using eyeglasses?

In a common-emitter transistor amplifier, what is the role of the emitter resistor, and how does it affect the amplifier's stability and gain?

What is the significance of the concept of 'distance of closest approach' that will determine the scattering that is more likely to have a gold atom?