List of top Physics Questions

A boat which has a speed of $5\, km/h$ in still water crosses a river of width $1\, km$ along the shortest possible path in $15\, min$. The velocity of the river water in $km/h$ is
If one mole of a monoatomic gas ($\gamma$ = 5/ 3) is mixed with one mole of a diatomic gas ($\gamma$ = 7 / 5), the value of $\gamma$ for the mixture is
A cylinder of radius R made of a material of thermal conductivity $K_1$, is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of a material of thermal conductivity K$_2$. The two ends of the combined system are maintained at two different temperatures. There is no loss of heat across the cylindrical surface and the system is in steady state. The effective thermal conductivity of the system is
A satellite $S$ is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of the earth. Then,
Let $I$ be the moment of inertia of a uniform square plate about an axis $AB$ that passes through its centre and is parallel to two of its sides. $CD$ is a line in the plane of the plate that passes through the centre of the plate and makes an angle $\theta$ with $AB$. The moment of inertia of the plate about the axis $CD$ is then equal to
The coefficient of restitution $e$, for a perfectly elastic collision is
A particle executes simple harmonic motion with a frequency f. The frequency with which its kinetic energy oscillates is
During a negative beta decay
A tube closed at one end containing air produces fundamental note of frequency $512\, Hz$. If the tube is open at both the ends, the fundamental frequency will be
A reference frame attached to the earth
Two thin long parallel wires separated by a distance b are carrying a current i ampere each. The magnitude of the force per unit length exerted by one wire on the other is
A simple pendulum of length L and mass (bob) M is oscillating in a plane about a vertical line between angular limits- $\phi$ and $+\phi$ For an angular displacement $\theta(| \theta |< \phi)$, the tension in the string and the velocity of the bob are T and v respectively. The following relations hold good under the above conditions
A proton moving with a constant velocity passes through a region of space without any change in its velocity. If E and B represent the electric and magnetic fields respectively. Then, this region of space may have
The X-ray beam coming from an X-ray tube will be
70 cal of heat are required to raise the temperature of2 moles of an ideal diatomic gas at constant pressure from 30$^{\circ}$C to 35$^{\circ}$C. The amount of heat required (in calorie) to raise the temperature of the same gas through the same range (30$^{\circ}$C to 35$^{\circ}$C) at constant volume is
A uniform chain of length $L$ and mass $M$ is lying on a smooth table and one third of its length is hanging vertically down over the edge of the table. If $g$ is acceleration due to gravity, work required to pull the hanging part on to the table is
A rectangular loop carrying a current i is situated near a long straight wire such that the wire is parallel to one of the sides of the loop and is in the plane of the loop. If steady current I is established in the wire as shown in the figure, the loop will
White light is used to illuminate the two slits in a Young's double slit experiment. The separation between the slits is b and the screen is at a distance d (>> b) from the slits. At a point on the screen directly in front of one of the slits, certain wavelengths are missing. Some of these missing wavelengths are
$L, C$ and $R$ represent the physical quantities inductance, capacitance and resistance respectively. The combinations which have the dimensions of frequency are
A box is moved along a straight line by a machine delivering constant power. The distance moved by the body in time $t$ is proportional to
A solid conducting sphere having a charge Q is surrounded by an uncharged concentric conducting hollow spherical shell. Let the potential difference between the surface of the solid sphere and that of the outer surface of the hollow shell be V. If the shell is now given a change of - 3Q, the new potential difference between the same two surfaces is
A ray of light from a denser medium strikes a rarer medium at an angle of incidence i (see figure). The reflected and refracted rays make an angle of $90^\circ$ with each other. The angles of reflection and refraction are r and r'. The critical angle is
The equation; \(4\space _1^1H \rightarrow _4^2{He}^2+2e^-+26 MeV\)
The current i in the circuit (see figure) is
A hollow metal sphere of radius 5 cm is charged such that the potential on its surface is 10 V. The potential at the centre of the sphere is.