List of top Physics Questions

The half-life of a radioactive substance is 12 minutes. The time gap between 28\% decay and 82\% decay of the radioactive substance is:
At room temperature, gaseous hydrogen is bombarded with a beam of electrons of 13.6 eV energy. The series to which the emitted spectral line belongs to:
If the amplitude of the magnetic field part of a harmonic electromagnetic wave in vacuum is \( 270 \) nT, the amplitude of the electric field part of the wave is:
In a series LCR circuit, if the current leads the source voltage, then:
An element consists of a mixture of three isotopes A, B, and C of masses \( m_1 \), \( m_2 \), and \( m_3 \) respectively. If the relative abundances of the three isotopes A, B, and C is in the ratio 2:3:5, the average mass of the element is:
A particle of charge \( 2 C \) is moving with a velocity \( (3\hat{i} + 4\hat{j}) \) m/s in the presence of magnetic and electric fields. If the magnetic field is \( ( \hat{i} + 2\hat{j} + 3\hat{k} ) \) T and the electric field is \( (-2\hat{k}) \) NC\(^{-1}\), then the Lorentz force on the particle is:
A rectangular coil of 400 turns and \(10^{-2} \, \text{m}^2\) area, carrying a current of 0.5 A is placed in a uniform magnetic field of 1 T such that the plane of the coil makes an angle of 60° with the direction of the magnetic field. The initial moment of force acting on the coil in Nm is:
The most exotic diamagnetic materials are:
Two circular coils of radii \(r_1\) and \(r_2\) (\(r_1 \ll r_2\)) are placed coaxially with their centers coinciding. The mutual inductance of the arrangement is:
The efficiency of a reversible heat engine working between two temperatures is 50\%. The coefficient of performance of a refrigerator working between the same two temperatures but in reverse direction is:
The total internal energy of 4 moles of a diatomic gas at a temperature of \(27^\circ C\) is: (Universal gas constant \( R = 8.31 \, \text{J mol}^{-1} \text{K}^{-1} \))
A car travelling at a speed of \(54 \, \text{kmph}\) towards a wall sounds a horn of frequency \(400 \, \text{Hz}\). The difference in the frequencies of two sounds, one received directly from the car and the other reflected from the wall, noticed by a person standing between the car and the wall is: (Speed of sound in air is \(335 \, \text{m/s}\))
For a combination of two convex lenses of focal lengths \( f_1 \) and \( f_2 \) to act as a glass slab, the distance of separation between them is:
If a ray of light passes through an equilateral prism such that the angle of incidence and the angle of emergence are both equal to 70\% of the angle of the prism, then the angle of minimum deviation is:
The temperature on a Fahrenheit temperature scale that is twice the temperature on a Celsius temperature scale is:
The temperatures of equal masses of three different liquids A, B, and C are \(15^\circ C\), \(24^\circ C\), and \(30^\circ C\) respectively. The resultant temperature when liquids A and B are mixed is \(20^\circ C\) and when liquids B and C are mixed is \(26^\circ C\). Then the ratio of specific heat capacities of the liquids A, B, and C is:
The height of water level in a tank of uniform cross-section is 5 m. The volume of the water leaked in 5 s through a hole of area \(2.4~mm^{2}\) made at the bottom of the tank is (Assume the level of the water in the tank remains constant and acceleration due to gravity \(=10~ms^{-2}\))
A steel wire of length 3 m and a copper wire of length 2.2 m are connected end to end. When the combination is stretched by a force, the net elongation is 1.05 mm. If the area of cross-section of each wire is 6 mm², then the load applied is: (Young’s moduli of steel and copper are respectively \(2 \times 10^{11} \, \text{Nm}^{-2}\) and \(1.1 \times 10^{11} \, \text{Nm}^{-2}\)).
The work done in increasing the diameter of a soap bubble from 2 cm to 4 cm is (Surface tension of soap solution \(=3.5\times10^{-2}Nm^{-1}\))
The energy required to take a body from the surface of the earth to a height equal to the radius of the earth is \( W \). The energy required to take this body from the surface of the earth to a height equal to twice the radius of the earth is:
A block of mass 0.5 kg is at rest on a horizontal table. The coefficient of kinetic friction between the table and the block is 0.2. If a horizontal force of 5 N is applied on the block, the kinetic energy of the block in a time of 4 s is (Acceleration due to gravity = 10 m/s\(^2\))
A body P is projected at an angle of 30° with the horizontal and another body Q is projected at angle of 30° with the vertical. If the ratio of the horizontal ranges of the bodies P and Q is 1:2, then the ratio of the maximum heights reached by the bodies P and Q is
A car is moving on a circular track banked at an angle of 45°. If the maximum permissible speed of the car to avoid slipping is twice the optimum speed of the car to avoid the wear and tear of the tyres, then the coefficient of static friction between the wheels of the car and the road is
A body is falling freely from the top of a tower of height 125 m. The distance covered by the body during the last second of its motion is \(x\%\) of the height of the tower. Then \(x\) is (Acceleration due to gravity = 10 m/s\(^2\))
Regarding fundamental forces in nature, the correct statement is