If copper wire is stretched to make its radius decrease by 0.1%, then the percentage change in its resistance is approximately
- A-0.4%
- B+0.8%
- C+0.4%
- D+0.2%
Question types
MODEL PAPER 2025 question types
38 questions across 6 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.
38
Questions
6
Question groups
5
Question types
01
M.C.Q (1 Marks)
12 Q→02Assertion (A) & Reason (B) MCQ
4 Q→032 Marks Questions
6 Q→043 Marks Question
8 Q→055 Marks Questions
6 Q→06Case study (4 Marks)
2 Q→Sample Questions
MODEL PAPER 2025 questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
The number of electrons made available for conduction by dopant atoms depends strongly upon
- Adoping level
- Bincrease in ambient temperature
- Cenergy gap
- Doptions (a) and (b) both
Colours observed on a CD (Compact Disk) is due to
- AReflection
- BDiffraction
- CDispersion
- DAbsorption
A point object is placed at the centre of a glass sphere of radius $6 \ cm$ and refractive index $1.5.$ The distance of virtual image from the surface of the sphere is
- A$2 \ cm$
- B$4 \ cm$
- ✓$6 \ cm$
- D$12 \ cm$
Answer: C.
View full solution →The distance of closest approach of an alpha particle is $d$ when it moves with a speed $V$ towards a nucleus.
Another alpha particle is projected with higher energy such that the new distance of the closest approach is $d/2.$ What is the speed of projection of the alpha particle in this case?
Another alpha particle is projected with higher energy such that the new distance of the closest approach is $d/2.$ What is the speed of projection of the alpha particle in this case?
- A$V / 2$
- ✓$\sqrt{2} V$
- C$2 V$
- D$4 V$
Answer: B.
View full solution →Assertion (A): de Broglie's wavelength of a freely falling body keeps decreasing with time.
Reason(R): The momentum of the freely falling body increases with time.
Reason(R): The momentum of the freely falling body increases with time.
- AIf both Assertion and Reason are true and Reason is the correct explanation of Assertion
- B
- C
- D
Assertion (A): Nuclei having mass number about 60 are least stable.
Reason(R): When two or more light nuclei are combined into a heavier nucleus then the binding energy per nucleon will decrease.
Reason(R): When two or more light nuclei are combined into a heavier nucleus then the binding energy per nucleon will decrease.
- A
- B
- C
- D
Assertion (A): In a hydrogen atom there is only one electron but its emission spectrum shows many lines.
Reason(R): In a given sample of hydrogen there are many atoms each containing one electron; hence many electrons in different atoms may be in different orbits so many transitions from higher to lower orbits are possible.
Reason(R): In a given sample of hydrogen there are many atoms each containing one electron; hence many electrons in different atoms may be in different orbits so many transitions from higher to lower orbits are possible.
- A
- B
- C
- D
Assertion (A): On increasing the current sensitivity of a galvanometer by increasing the number of turns may not necessarily increase its voltage sensitivity.
Reason(R): The resistance of the coil of the galvanometer increases on increasing the number of turns.
Reason(R): The resistance of the coil of the galvanometer increases on increasing the number of turns.
- A
- B
- C
- D
What should be the radius ‘r’ of nearest possible orbits of satellite of mass ‘m’ revolving around the planet of mass ‘M’ as per Bohr Postulates in terms of m, M, G, h where G is Gravitational constant and h is plank’s constant.
Binding energy per nucleon vs mass number curve for nuclei is shown in the figure. W, X, Y and Z are four nuclei indicated on the curve. Identify which of the following nuclei is most likely to undergo
(i) Nuclear Fission
(ii) Nuclear Fusion.
Justify your answer.
(i) Nuclear Fission
(ii) Nuclear Fusion.
Justify your answer.
$P$ and $Q$ are two identical charged particles each of mass $4 \times 10^{-26} kg$ and charge $4.8 \times 10^{-19} C$, each moving with the same speed of $2.4 \times 10^5 m / s$ as shown in the figure. The two particles are equidistant $(0.5 m)$ from the vertical $Y -$axis. At some instant, a magnetic field $B$ is switched on so that the two particles undergo head$-$on collision.
Find $–$
$(I)$ the direction of the magnetic field and
$(II)$ the magnitude of the magnetic field applied in the region.
View full solution →Find $–$
$(I)$ the direction of the magnetic field and
$(II)$ the magnitude of the magnetic field applied in the region.
A beam of light consisting of two wavelengths, $4000 \mathring A$ and $6000 \mathring A ,$ is used to obtain interference fringes in a Young’s double$-$slit experiment. What is the least distance from the central maximum where the dark fringe is obtained?
View full solution →In Young’s double-slit experiment using monochromatic light of wavelength $\lambda $, the intensities of two sources is I. What is the intensity of light at a point where path difference between wave front is $\lambda / 4$ ?
View full solution →$(II) \ (a)$ Define electric flux and write its SI unit.
$(b)$ Use Gauss᾿s law to obtain the expression for the electric field due to a uniformly charged infinite plane sheet of charge.
View full solution →$(b)$ Use Gauss᾿s law to obtain the expression for the electric field due to a uniformly charged infinite plane sheet of charge.
State Gauss᾿s theorem in electrostatics. Using this theorem, derive an expression for the electric field due to an infinitely long straight wire of linear charge density $\lambda$.
View full solution →A light ray entering a right $-$ angled prism undergoes refraction at the face $AC$ as shown in Figure
$(I)$ What is the refractive index of the material of the prism in Figure?
$(II) \ (a) $ If the side $AC$ of the above prism is now surrounded by a liquid of refractive index $\frac{2}{\sqrt{3}}$ as shown in Figure, determine if the light ray continues to graze along the interface $AC$ or undergoes total internal reflection or undergoes refraction into the liquid.
$(b)$ Draw the ray diagram to represent the path followed by the incident ray with the corresponding angle values.
$($Given, $\sin ^{-1}\left(\frac{\sqrt{2}}{\sqrt{3}}\right)=54.6^{\circ})$
View full solution →$(I)$ What is the refractive index of the material of the prism in Figure?
$(II) \ (a) $ If the side $AC$ of the above prism is now surrounded by a liquid of refractive index $\frac{2}{\sqrt{3}}$ as shown in Figure, determine if the light ray continues to graze along the interface $AC$ or undergoes total internal reflection or undergoes refraction into the liquid.
$(b)$ Draw the ray diagram to represent the path followed by the incident ray with the corresponding angle values.
$($Given, $\sin ^{-1}\left(\frac{\sqrt{2}}{\sqrt{3}}\right)=54.6^{\circ})$
A boy is holding a smooth, hollow and non-conducting pipe vertically with charged spherical ball of mass 10 g carrying a charge of +10 mC inside it which is free to move along the axis of the pipe. The boy is moving the pipe from East to West direction in the presence of magnetic field of 2T. With what minimum velocity, should the boy move the pipe such that the ball does not move along the axis. Also determine the direction of the magnetic field.
(I) Draw the energy band diagram for P-type semiconductor at (i) T=0K and (ii) room temperature.
(II) In the given diagram considering an ideal diode, in which condition will the bulb glow
(a) when the switch is open
(b) when the switch is closed
Justify your answer.
(II) In the given diagram considering an ideal diode, in which condition will the bulb glow
(a) when the switch is open
(b) when the switch is closed
Justify your answer.
$(II)$ A compound microscope consists of an objective lens of focal length $2.0 \ cm$ and an eyepiece of focal length $6.25 \ cm$ separated by a distance of $15 \ cm$. How far from the objective should an object be placed in order to obtain the final image at
$(a)$ the least distance of distinct vision $(25 \ cm)$ and
$(b)$ infinity? What is the magnifying power of the microscope in each case?
View full solution →$(a)$ the least distance of distinct vision $(25 \ cm)$ and
$(b)$ infinity? What is the magnifying power of the microscope in each case?
$(I) (a)$ A giant refracting telescope at an observatory has an objective lens of focal length $15 m$. If an eyepiece of focal length $1.0 \ cm$ is used, what is angular magnification of the telescope in normal adjustment?
$(b)$ If this telescope is used to view the moon, what is the diameter of the image of the moon formed by the objective lens? The diameter of the moon is $3.48 \times 10^6 m$ and the radius of lunar orbit is $3.8 \times 10^8 m$.
View full solution →$(b)$ If this telescope is used to view the moon, what is the diameter of the image of the moon formed by the objective lens? The diameter of the moon is $3.48 \times 10^6 m$ and the radius of lunar orbit is $3.8 \times 10^8 m$.
(II) (a) With the help of a diagram, explain the principle of a device which changes a low ac voltage into a high voltage . Deduce the expression for the ratio of secondary voltage to the primary voltage in terms of the ratio of the number of turns of primary and secondary winding. For an ideal transformer, obtain the ratio of primary and secondary currents in terms of the ratio of the voltages in the secondary and primary coils.
(b) Write any two sources of the energy losses which occur in actual transformers.
(c) A step-up transformer converts a low input voltage into a high output voltage. Does it violate law of conservation of energy? Explain.
(b) Write any two sources of the energy losses which occur in actual transformers.
(c) A step-up transformer converts a low input voltage into a high output voltage. Does it violate law of conservation of energy? Explain.
$(I)$ Explain briefly, with the help of a labelled diagram, the basic principle of the working of an a.c. generator. In an a.c. generator, coil of $N$ turns and area $A$ is rotated at an angular velocity $ω$ in a uniform magnetic field $B$. Derive an expression for the instantaneous value of the emf induced in coil. What is the source of energy generation in this device?
View full solution →(II) (a) Using Kirchhoff'᾿s laws obtain the equation of the balanced state in Wheatstone bridge.
b) A wire of uniform cross-section and resistance of 12 ohm is bent in the shape of circle as shown in the figure. A resistance of 10 ohms is connected to diametrically opposite ends C and D. A battery of emf 8V is connected between A and B. Determine the current flowing through arm AD.
b) A wire of uniform cross-section and resistance of 12 ohm is bent in the shape of circle as shown in the figure. A resistance of 10 ohms is connected to diametrically opposite ends C and D. A battery of emf 8V is connected between A and B. Determine the current flowing through arm AD.
Motion of Charge in Magnetic Field
An electron with speed $V_0$ << c moves in a circle of radius $r _{\circ}$ in a uniform magnetic field. This electron is able to traverse a circular path as the magnetic force acting on the electron is perpendicular to both $V_0$ and B ,as shown in the figure. This force continuously deflects the particle sideways without changing its speed and the particle will move along a circle perpendicular to the field. The time required for one revolution of the electron is $T _{ o }$.
(i) If the speed of the electron is now doubled to 2vo. The radius of the circle will change to
(A) $4 r_0$ (B) $2 r_0$ (C) $r _{ o }$ (D) $r _0 / 2$
(ii) If v = 2vo, then the time required for one revolution of the electron (To ) will change to
(A) $4 T_0$ (B) $2 T_{ O }$ (C) $T _{ o }$ (D) $T _{ d } / 2$
(iii) A charged particles is projected in a magnetic field . The acceleration of the particle is found to be. Find the value of x.
(A) $4 ms^{-2}$ (B) $-4 ms^{-2}$ (C) $-2 ms^{-2}$ (D) $2 ms^{-2}$
(iv) If the given electron has a velocity not perpendicular to B, then trajectory of the electron is
(A) straight line (B) circular (C) helical (D) zig-zag
OR
If this electron of charge (e) is moving parallel to uniform magnetic field with constant velocity v, the force acting on the electron is
(A) Bev (B) Be/v (C) B/ev (D) Zero
View full solution →An electron with speed $V_0$ << c moves in a circle of radius $r _{\circ}$ in a uniform magnetic field. This electron is able to traverse a circular path as the magnetic force acting on the electron is perpendicular to both $V_0$ and B ,as shown in the figure. This force continuously deflects the particle sideways without changing its speed and the particle will move along a circle perpendicular to the field. The time required for one revolution of the electron is $T _{ o }$.
(i) If the speed of the electron is now doubled to 2vo. The radius of the circle will change to
(A) $4 r_0$ (B) $2 r_0$ (C) $r _{ o }$ (D) $r _0 / 2$
(ii) If v = 2vo, then the time required for one revolution of the electron (To ) will change to
(A) $4 T_0$ (B) $2 T_{ O }$ (C) $T _{ o }$ (D) $T _{ d } / 2$
(iii) A charged particles is projected in a magnetic field . The acceleration of the particle is found to be. Find the value of x.
(A) $4 ms^{-2}$ (B) $-4 ms^{-2}$ (C) $-2 ms^{-2}$ (D) $2 ms^{-2}$
(iv) If the given electron has a velocity not perpendicular to B, then trajectory of the electron is
(A) straight line (B) circular (C) helical (D) zig-zag
OR
If this electron of charge (e) is moving parallel to uniform magnetic field with constant velocity v, the force acting on the electron is
(A) Bev (B) Be/v (C) B/ev (D) Zero
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