CBSE 12 Physics Question Paper-2025 Set-2

Two identical point charges are placed at the two vertices A and B of an equilateral triangle of side l. The magnitude of the electric field at the third vertex P is E. If a hollow conducting sphere of radius (l/4) is placed at P, the magnitude of the electric field at point P now becomes

A coil of an ac generator with 100 turns and each turn of area 0.1 m^2 rotates half a revolution per second in a magnetic field of 0.02 T. The maximum emf generated in the coil is -

Atomic spectral emission lines of hydrogen atom are incident on a zinc surface. The lines which can emit photoelectrons from the surface are members of

The energy of an electron in a hydrogen atom in ground state is -13.6 eV. The energy of the electron when it makes a transition to a state where its kinetic energy is 1.7 eV, is -

In a p-type Si-semiconductor, an acceptor atom is added on an average of one atom per 5 x 10^7 silicon atoms. If the number density of silicon atoms in the sample is 5 x 10^28 atoms per cubic meter, the number of holes per cubic centimeter created by doping in the sample will be -

Two monochromatic waves of intensity I and 4I interfere. The ratio of maximum to minimum intensity in the resulting wave is -

The total energy of an electron in the ground state of a hydrogen atom is -13.6 eV. What will be the total energy of the electron when it makes a transition to a state where its kinetic energy is 1.7 eV?

In a p-type Si-semiconductor, an acceptor atom is added on an average of one atom per 5 x 10^7 silicon atoms. If the number density of silicon atoms in the sample is 5 x 10^28 atoms per cubic meter, the number of holes per cubic centimeter created by doping in the sample will be -

Two light waves of intensity I each, interfere at a point on the screen where the path difference is λ/8. The intensity at this point will be -

In a diffraction experiment, the slit is illuminated by light of wavelength 600 nm. The first minimum of the diffraction pattern falls at θ = 30°. The width of the slit will be -

Assertion (A) : An ideal step-down transformer does not dissipate electric energy. Reason (R) : In a step-down transformer, the voltage decreases but the current increases.

A charge Q is distributed uniformly over a large non-conducting sheet of area A. A student wants to measure the electric field in front of the sheet. For this purpose, the student keeps a positively charged particle at a distance 'r' from the sheet. The electric field at this point is E. Now the student removes this charged particle and puts a negatively charged particle at the same distance. The electric field at this point now will be

Two monochromatic waves of intensity I and 4I interfere. The ratio of maximum to minimum intensity in the resulting wave is -

In a p-type Si-semiconductor, an acceptor atom is added on an average of one atom per 5 x 10^7 silicon atoms. If the number density of silicon atoms in the sample is 5 x 10^28 atoms per cubic meter, the number of holes per cubic centimeter created by doping in the sample will be -

The total energy of an electron in the ground state of a hydrogen atom is -13.6 eV. What will be the total energy of the electron when it makes a transition to a state where its kinetic energy is 1.7 eV?

Two conductors A and B of the same material have their lengths in the ratio 1:2 and radii in the ratio 2:3. If they are connected in parallel across a battery, the ratio of the drift velocities of electrons in them will be -

The ratio of the number of turns of the primary to the secondary coils in an ideal transformer is 20: 1. If 240 V ac is applied from a source to the primary coil of transformer and a 6.0 ohm resistor is connected across the output terminals, then current drawn by the transformer from the source will be -

A coil with diameter 15 mm and 300 turns is placed in a magnetic field of 30 mT such that the plane of the coil is perpendicular to the direction of the magnetic field. The field intensity is uniformly decreased to zero in 20 ms and then again uniformly increased to 30 mT in 40 ms. If the induced emf in the two time intervals are e1 and e2 respectively, the value of e1/e2 is -

In the diagram, the variation of Coulomb's force (F) with 1/r^2 is shown between two point charges. Here r is the separation between the two charges (q1, q2) and (q2, q3). If q2 is positive and its magnitude is minimum then the magnitudes of q1, q2 and q3 are such that:

A coil has 100 turns, each of area 0.05 m^2 and its total resistance is 1.5 Ω. The coil is immersed in a magnetic field of 90 mT at an instant with its axis parallel to the field. At the same instant, the induced charge in the coil is -

Assertion (A) : An ideal step-down transformer does not dissipate electric energy. Reason (R) : In a step-down transformer, the voltage decreases but the current increases.

A charge Q is distributed uniformly over a large non-conducting sheet of area A. A student wants to measure the electric field in front of the sheet. For this purpose, the student keeps a positively charged particle at a distance 'r' from the sheet. The electric field at this point is E. Now the student removes this charged particle and puts a negatively charged particle at the same distance. The electric field at this point now will be

Two charges -q each are placed at the vertices A and B of an equilateral triangle ABC. If M is the mid-point of AB, the net electric field at C will point along

An ac source is connected to an ideal transformer. This transformer supplies 3000 V to a device through its secondary coil. If the primary voltage is 200 V, the number of turns in its secondary coil is -

Which one of the following statements is correct? (A) conservative and field lines do not form closed loops. (B) conservative and field lines form closed loops. (C) non-conservative and field lines do not form closed loops. (D) non-conservative and field lines form closed loops.

Two identical point charges are placed at the two vertices A and B of an equilateral triangle of side l. The magnitude of the electric field at the third vertex P is E. If a hollow conducting sphere of radius (l/4) is placed at P, the magnitude of the electric field at point P now becomes

A coil of an ac generator with 100 turns and each turn of area 0.1 m^2 rotates half a revolution per second in a magnetic field of 0.02 T. The maximum emf generated in the coil is -

Atomic spectral emission lines of hydrogen atom are incident on a zinc surface. The lines which can emit photoelectrons from the surface are members of

The energy of an electron in a hydrogen atom in ground state is -13.6 eV. The energy of the electron when it makes a transition to a state where its kinetic energy is 1.7 eV, is -

In a p-type Si-semiconductor, an acceptor atom is added on an average of one atom per 5 x 10^7 silicon atoms. If the number density of silicon atoms in the sample is 5 x 10^28 atoms per cubic meter, the number of holes per cubic centimeter created by doping in the sample will be -