List of top Physics Questions

27 water droplets of radius 3 mm each and charged with the same charge are coalesced to form a big water drop. The ratio of surface charge density of the small drop and large drop will be

Consider a rope fixed at both ends under tension so that it is horizontal (i.e. assume the rope is along x-axis, with gravity acting along z-axis). Now the right end is continually oscillated at high frequency n (say n=100 Hz) horizontally and in a direction along the rope; amplitude of oscillation is negligible. The oscillation travells along the rope and is reflected at the left end. 
Let the total length of rope be l, total mass be m and the acceleration due to gravity be g. 
After initial phase (say a mintue or so), the rope has __(BLANK-1)__ wave, which is __(BLANK-2)__ in nature. It results from superposition of left travelling and right travelling __(BLANK-3)__ waves. This resulting wave has a frequency __ (BLANK-4)_ that of oscillation frequency nu. Simple dimensional analysis indicates that the frequency of can be of the form: ___(BLANK-5)__ .

The quantity of heat conducted through a metal rod kept at its ends at 100°C and 120°C is 5 J/s. If the ends are kept at 200°C and 220°C, then the quantity of heat conducted in 10 seconds is:
The torque required to increase the angular speed of a uniform solid disc of mass 10 kg and diameter 0.5 m from zero to 120 rotations per minute in 5 sec is:
In an LCR series circuit, the value of only capacitance \( C \) is varied. The resulting variation of resonance frequency \( f_0 \) as a function of \( C \) can be represented as

The tension applied to a metal wire of one metre length produces an elastic strain of 1%. The density of the metal is \( 8000 \, kg/m^3 \) and Young's modulus of the metal is \( 2 \times 10^{11} \, Nm^{-2} \). The fundamental frequency of the transverse waves in the metal wire is: 

Consider the following logic circuit. The circuit consists of three gates: an AND gate, an OR gate, and a NOT gate. The inputs to the AND gate are \( A = 1 \) and \( B = 0 \). The output of the AND gate is fed into the input of the OR gate, which has another input \( C = 1 \). The output of the OR gate is then passed through a NOT gate. What is the final output of the circuit?
What is the output of a NAND gate when both inputs are HIGH?
Which of the following is NOT a layer of the urinary bladder?
The coefficient of performance of a refrigerator is 5. If the temperature inside the freezer is \( -20^\circ \mathrm{C} \), what is the temperature of the surroundings to which it rejects heat?
A wheel of diameter 20 cm is rotating at 600 rpm. The linear velocity of a particle at its rim is:

Figure shows a part of an electric circuit. The potentials at points \( a, b, \text{and} \, c \) are \( 30 \, \text{V}, 12 \, \text{V}, \, \text{and} \, 2 \, \text{V} \), respectively. The current through the \( 20 \, \Omega \) resistor will be: 

The value of acceleration due to gravity at Earth's surface is \( 9.8 \, \text{m/s}^2 \). The altitude above its surface at which the acceleration due to gravity decreases to \( 4.9 \, \text{m/s}^2 \) is close to: (Radius of Earth \( R = 6.4 \times 10^6 \, \text{m} \))
The ratio of the shortest wavelength of the Balmer series to the shortest wavelength of the Paschen series is:
Two charges \( q_1 = 2 \, \mu \mathrm{C} \) and \( q_2 = -3 \, \mu \mathrm{C} \) are placed 10 cm apart in a vacuum. What is the magnitude and direction of the force between them?
A particle performs SHM, having a speed of 6 cm/sec at the mean position and an amplitude of 4 cm. Find the position of the particle from the mean position when its velocity is 2 cm/sec.
A cylinder of fixed capacity \( 67.2 \, \mathrm{L} \) contains helium gas at STP. The amount of heat needed to raise the temperature of the gas in the cylinder by \( 20^\circ \mathrm{C} \) is:
A vessel completely filled with water has holes A and B at depths \( h \) and \( 3h \) from the top, respectively. Hole A is a square of side \( L \), and B is a circle of radius \( r \). The water flowing out per second from both the holes is the same. Then \( L \) is equal to:
The electrostatic potential due to an electric dipole at a distance \( r \) varies as:
Convert 72 degrees Celsius to Fahrenheit.
What is the magnetic field produced inside a solenoid?
Two projectiles are projected at \( 30^\circ \) and \( 60^\circ \) with the horizontal with the same speed. The ratio of the maximum height attained by the two projectiles respectively is:
Find the solubility product of \( \mathrm{Ba(OH)_2} \)?
Where \( S = 1.73 \times 10^{-14} \).
Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon:
A coil has a resistance of \( 30 \, \Omega \) and an inductive reactance of \( 20 \, \Omega \) at 50 Hz frequency. If an AC source of 200 V and 100 Hz is connected across the coil, then how much current will flow through the coil?