Pre-Board Examination 2026
Subject – Physics | M.M.–56
Subject – Physics | M.M.–56
Score: 0 / 18
Q.1. Multiple choice questions. (½ × 18 = 9)
1. Two charges placed in air repel each other with a force of 10⁻⁴ N. If oil is filled between the two charges, the force becomes 2.5 × 10⁻⁵ N. What will be the dielectric constant of the oil?
✔ Correct Answer : 4
2. If an electron and a proton are located at a distance of 1A°, then the electric dipole moment of the system is:-
✔ Correct Answer : 1.6×10⁻²⁹ C·m
3. Two opposite charges of magnitude q are placed at a distance of 2d from each other, the potential at their midpoint will be:-
✔ Correct Answer : Zero
4. Which of the following decreases in resistance with increase in temperature?
✔ Correct Answer : Germanium
5. If 1 ampere electric current flows in two long straight and parallel wires situated at a distance of one meter from each other in vacuum, then what will be the magnetic force generated per meter length of each of these conductors?
✔ Correct Answer : 2×10⁻⁷ N
6. If the relative permittivity of a substance is 1.00001 then the substance will be.
✔ Correct Answer : Paramagnetic
7. The value of magnetic energy stored in an inductance is.
✔ Correct Answer : LI²/2
8. The inductance of the square coil is 5 H. The current flowing through it is increasing at the rate of 2 A/s. The induced emf will be
✔ Correct Answer : 10V
9. In the resonance state, there is a phase difference between voltage and current.
✔ Correct Answer : 0
10. In T.V. remote controller the electromagnetic waves generated is:-
✔ Correct Answer : Infra red waves
11. If the refractive index of the material of an equilateral prism is √3, then its angle of minimum deviation will be
✔ Correct Answer : 60
12. What will be the focal length of a convex lens whose power is 2.5D?
✔ Correct Answer : 40cm
13. Due to which effect is the colour visible in CD?
✔ Correct Answer : Diffraction
14. The value of photoelectric current depends on.
✔ Correct Answer : only on the intensity of light
15. Which range of the hydrogen spectrum lies in the visible region of the spectrum?
✔ Correct Answer : Balmer series
16. The mass energy of 1 amu is
✔ Correct Answer : 931MeV
17. Which current causes the formation of depletion layers?
✔ Correct Answer : Diffusion current
18. The capacity of the parallel plate capacitor increases when
✔ Correct Answer : area of the plate is increased
Q.2. Fill in the blanks. (½ × 10 = 5)
(i) The value of potential on the axial line of an electric dipole is _______________.
(ii) The average time between two consecutive collisions is called the ______ of the free electron.
(iii) The distance travelled by a particle along the magnetic field in one rotation is called __________.
(iv) The ability of a magnet to attract magnetic substances towards itself by its magnetic pole is called ………..
(v) Faraday’s law is based on conservation of…… ..
(vi) The value of the product of electric and magnetic field vectors at any point of electromagnetic wave propagation is equal to …………..
(vii) The power of converging len is……….. and the power of diverging lens is……………..
(viii) When the vibrations of the electric vector are confined to a particular direction or plane, the light is called …………….
(ix) If the intensity of incident light is doubled, its frequency remains ………………
(x) A certain minimum energy is required to remove electrons from a metal surface. This minimum energy is called the ……of the metal.
Q.3. Answer the following questions in one line. (1 × 10 = 10)
(i) The value of potential on the axial line of an electric dipole is _______________.
(ii) The average time between two consecutive collisions is called the ______ of the free electron.
(iii) The distance travelled by a particle along the magnetic field in one rotation is called __________.
(iv) The ability of a magnet to attract magnetic substances towards itself by its magnetic pole is called ………..
(v) Faraday’s law is based on conservation of…… ..
(vi) The value of the product of electric and magnetic field vectors at any point of electromagnetic wave propagation is equal to …………..
(vii) The power of converging len is……….. and the power of diverging lens is……………..
(viii) When the vibrations of the electric vector are confined to a particular direction or plane, the light is called …………….
(ix) If the intensity of incident light is doubled, its frequency remains ………………
(x) A certain minimum energy is required to remove electrons from a metal surface. This minimum energy is called the ……of the metal.
(i) Why does the resistivity of conductors increase with increase in temperature?
(ii) Write the vector form of Ohm’s law.
(iii) What is magnetic susceptibility?
(iv) Show the magnetic field lines due to an external magnetic field near a diamagnetic substance.
(v) A copper ring is suspended in a vertical plane by a thread. The north pole of a magnet is brought horizontally toward the ring. What effect will this have on the position of the ring?
(vi) If the magnetic field in an electromagnetic wave is B = 2×10⁻⁷ Sin (0.5×10³x + 1.5×10¹¹ t) T, then what will be the wavelength and frequency of the wave?
(vii) Describe the type of wavefront emanating from a point light source and represent it with a diagram.
(viii) Write the necessary conditions for the occurrence of photoelectric effect.
(ix) Write two drawbacks of Bohr's model.
(x) Write the order of density of the uranium nucleus.
(ii) Write the vector form of Ohm’s law.
(iii) What is magnetic susceptibility?
(iv) Show the magnetic field lines due to an external magnetic field near a diamagnetic substance.
(v) A copper ring is suspended in a vertical plane by a thread. The north pole of a magnet is brought horizontally toward the ring. What effect will this have on the position of the ring?
(vi) If the magnetic field in an electromagnetic wave is B = 2×10⁻⁷ Sin (0.5×10³x + 1.5×10¹¹ t) T, then what will be the wavelength and frequency of the wave?
(vii) Describe the type of wavefront emanating from a point light source and represent it with a diagram.
(viii) Write the necessary conditions for the occurrence of photoelectric effect.
(ix) Write two drawbacks of Bohr's model.
(x) Write the order of density of the uranium nucleus.
SHORT ANSWERS TYPE QUESTION. (10 × 1.5 = 15)
Q.4. Obtain an expression for the electric potential energy of a system of two charges. 1½
Q.5. A pair of adjacent coils has a mutual inductance of 1.5 H. If the current in one coil changes from 0 A to 20 A in 0.5 seconds, how much will the magnetic flux in the other coil change? 1½
Q.6. Prove that the peak value of alternating current is √2 times its root mean square value. 1½
Q.7. A concave lens of focal length 30 cm is placed in contact with a convex lens of focal length 20 cm. Find the focal length of the combined lens. 1½
Q.8. Prove that for the phenomenon of interference:-
I = 4I₀ cos²(ϕ/2) 1½
Q.9. The displacement produced at a point by two phase-related sources is Y1 = acoswt and Y2 = acos(wt + 2π/3) respectively, then find the resultant displacement. 1½
Q.10. Explain de Broglie’s hypothesis. 1½
Q.11. Calculate the radius of the dynamically stable orbit and the total energy of its electron in the hydrogen atom for the Rutherford nuclear model of the atom. 1½
Q.12. Write any four properties of nuclear forces. 1½
Q.13. What is the barrier potential in a p-n junction diode? How will it form, explain? 1½
LONG ANSWERED TYPE QUESTIONS (3 × 3 = 9)
Q.14. Using Gauss's law, determine the electric field intensity due to a charged spherical conductor. Draw the necessary diagrams. 3
OR
Using Gauss’s law, determine the electric field intensity due to a uniformly charged conductor plate. Draw the necessary diagram. 3
Q.15. (i) A 15uF capacitor is connected to a 220V, 50Hz source. Find the capacitive reactance of the circuit. 1½
(ii) In A.C circuit capacitor is connected to voltage source. Prove that current is leads by angle 90 with respect to voltage. Draw phasor diagram also. 1½
OR
(i) Draw a phasor diagram for an LCR circuit and derive an expression for its impedance. 1½
(ii) In an LCR circuit, L = 2H, C = 32uF, find the resonant frequency. 1½
Q.16. What is a semiconductor? Explain N and P type semiconductors with diagrams. 3
OR
Define rectification and explain its working by drawing a circuit diagram of a half-wave rectifier. 3
LONG ANSWERED TYPE QUESTIONS (4 × 2 = 8)
Q.17. What is meant by a compound microscope? Draw a diagram of how a compound microscope produces images. Briefly describe its working mechanism and derive a formula for its total magnification.
OR
Define refraction and derive the relation between object distance (u), image distance (v) and focal length (f).
Q.18. Write Ampere’s circuital law. Derive an expression for the magnetic field inside a long current-carrying solenoid. Draw the necessary diagrams.
OR
Derive the formula for the magnetic force between two parallel current carrying conductors.