List of top Physics Questions

Statement I : Two forces \((\vec{p} + \vec{q})\) and \((\vec{p} - \vec{q})\) where \(\vec{p} \perp \vec{q}\), when act at an angle \(\theta_1\) to each other, the magnitude of their resultant is \(\sqrt{3(p^2 + q^2)}\), when they act at an angle \(\theta_2\), the magnitude of their resultant becomes \(\sqrt{2(p^2 + q^2)}\). This is possible only when \(\theta_1<\theta_2\).
Statement II : In the situation given above, \(\theta_1 = 60^{\circ}\) and \(\theta_2 = 90^{\circ}\).
In the light of the above statements, choose the most appropriate answer from the options given below :
Statement I : If three forces \(\vec{F_1}\), \(\vec{F_2}\) and \(\vec{F_3}\) are represented by three sides of a triangle and \(\vec{F_1} + \vec{F_2} = -\vec{F_3}\), then these three forces are concurrent forces and satisfy the condition for equilibrium.
Statement II : A triangle made up of three forces \(\vec{F_1}\), \(\vec{F_2}\) and \(\vec{F_3}\) as its sides taken in the same order, satisfy the condition for translatory equilibrium.
In the light of the above statements, choose the most appropriate answer from the options given below :
If velocity [V] time [T] and force [F] are chosen as the base quantities, the dimensions of the mass will be :
Two thin metallic spherical shells of radii \(r_1\) and \(r_2\) (\(r_1<r_2\)) are placed with their centres coinciding. A material of thermal conductivity K is filled in the space between the shells. The inner shell is maintained at temperature \(\theta_1\) and the outer shell at temperature \(\theta_2\) (\(\theta_1<\theta_2\)). The rate at which heat flows radially through the material is :
A free electron of 2.6 eV energy collides with a \(H^+\) ion. This results in the formation of a hydrogen atom in the first excited state and a photon is released. Find the frequency of the emitted photon. (\(h = 6.6 \times 10^{-34}\) J s)

A capacitor of \( 50 \, \mu F \) is connected in a circuit as shown in figure. The charge on the upper plate of the capacitor is \(\dots\dots\dots\) \( \mu C \). 

The voltage drop across \( 15 \, \Omega \) resistance in the given figure will be \(\dots\dots\) V. 

Match List - I with List - II 

Choose the most appropriate answer from the option given below : 
 

A sample of a radioactive nucleus A disintegrates to another radioactive nucleus B, which in turn disintegrates to some other stable nucleus C. Plot of a graph showing the variation of number of atoms of nucleus B versus time is : (Assume that at t=0, there are no B atoms in the sample) 

In the following logic circuit the sequence of the inputs A, B are (0, 0), (0, 1), (1, 0) and (1, 1). The output Y for this sequence will be : 

Choose the correct waveform that can represent the voltage across R of the following circuit, assuming the diode is ideal one : 

The electric field in an electromagnetic wave is given by \( E = (50 \, NC^{-1}) \sin \omega (t - x/c) \). The energy contained in a cylinder of volume V is \( 5.5 \times 10^{-12} \, J \). The value of V is \(\dots\dots\dots\) \( cm^3 \).
(given \( \epsilon_0 = 8.8 \times 10^{-12} \, C^2 N^{-1} m^{-2} \))
If the sum of the heights of transmitting and receiving antennas in the line of sight of communication is fixed at \( 160 \, m \), then the maximum range of LOS communication is \(\dots\dots\dots\) km.
(Take radius of Earth \( = 6400 \, km \))
A square shaped wire with resistance of each side \( 3 \, \Omega \) is bent to form a complete circle. The resistance between two diametrically opposite points of the circle in unit of \( \Omega \) will be \(\dots\dots\dots\).
When a rubber ball is taken to a depth of \(\dots\dots\dots\) m in deep sea, its volume decreases by \( 0.5% \).
(The bulk modulus of rubber \(= 9.8 \times 10^8 \, Nm^{-2} \)
Density of sea water \(= 10^3 \, kg m^{-3} \)
\( g = 9.8 \, m/s^2 \))
A block moving horizontally on a smooth surface with a speed of \( 40 \, ms^{-1} \) splits into two equal parts. If one of the parts moves at \( 60 \, ms^{-1} \) in the same direction, then the fractional change in the kinetic energy will be \( x : 4 \) where \( x = \dots\dots\dots \).
A wire having a linear mass density \( 9.0 \times 10^{-4} \, kg/m \) is stretched between two rigid supports with a tension of \( 900 \, N \). The wire resonates at a frequency of \( 500 \, Hz \). The next higher frequency at which the same wire resonates is \( 550 \, Hz \). The length of the wire is \(\dots\dots\dots\) m.
A car is moving on a plane inclined at \( 30^\circ \) to the horizontal with an acceleration of \( 10 \, ms^{-2} \) parallel to the plane upward. A bob is suspended by a string from the roof of the car. The angle in degrees which the string makes with the vertical is \(\dots\dots\dots\). (Take \( g = 10 \, ms^{-2} \))
A particle of mass \( 1 \, kg \) is hanging from a spring of force constant \( 100 \, Nm^{-1} \). The mass is pulled slightly downward and released so that it executes free simple harmonic motion with time period T. The time when the kinetic energy and potential energy of the system will become equal, is \( \frac{T}{x} \). The value of x is \(\dots\dots\dots\).
A body of mass M moving at speed \(V_0\) collides elastically with a mass 'm' at rest. After the collision, the two masses move at angles \(\theta_1\) and \(\theta_2\) with respect to the initial direction of motion of the body of mass M. The largest possible value of the ratio M/m, for which the angles \(\theta_1\) and \(\theta_2\) will be equal, is :
A helicopter is flying horizontally with a speed 'v' at an altitude 'h' has to drop a food packet for a man on the ground. What is the distance of helicopter from the man when the food packet is dropped ?
The masses and radii of the earth and moon are (\(M_1, R_1\)) and (\(M_2, R_2\)) respectively. Their centres are at a distance 'r' apart. Find the minimum escape velocity for a particle of mass 'm' to be projected from the middle of these two masses :
A uniform heavy rod of weight \(10\,\text{kg}\,\text{ms}^{-2}\), cross-sectional area \(100\,\text{cm}^2\) and length \(20\,\text{cm}\) is hanging from a fixed support. Young modulus of the material of the rod is \(2 \times 10^{11}\,\text{Nm}^{-2}\). Neglecting the lateral contraction, find the elongation of rod due to its own weight :
Angular momentum of a single particle moving with constant speed along circular path :
Two particles A and B having charges \(20\,\mu C\) and \(-5\,\mu C\) respectively are held fixed with a separation of \(5\,\text{cm}\). At what position a third charged particle should be placed so that it does not experience a net electric force ?