List of practice Questions

A $10\, kW$ drilling machine is used to drill a bore in a small aluminium block of mass $8 \,kg$. Find the rise in temperature of the block in $2.5$ minutes, assuming $50\%$ power is used up in heating the machine itself or lost to the surroundings. (Specific heat of aluminium $= 0.91\, J \,g^{-1} \,^{\circ}C^{-1}$)
The $B-H$ curve for a ferromagnet is shown in the figure. The ferromagnet is placed inside a long solenoid with $1000 \, turns \, cm^{- 1}$ . The current that should be passed in the solenoid to demagnetise the ferromagnet completely is
The magnetic field at the point of intersection of diagonals of a square loop of side $L$ carrying a current $I$ is
Mixed $He^{+}$ and $O^{2 +}$ ions (mass of $H e^{+}=4 \, amu \, and \, that \, of \, O^{2 +}=16 \, amu$ ) beam passes a region of constant perpendicular magnetic field. If kinetic energy of all the ions is same, then
A $ 1\, kg $ block situated on a rough incline is connected to a spring of negligible mass having spring constant $ 100\, N\,m^{-1} $ as shown in the figure.
The block is released from rest with the spring in the unstretched position. The block moves $ 10\, cm $ down the incline before coming to rest. The coefficient of friction between the block and the incline is (Take $ g = 10\, ms^{-2} $ and assume that the pulley is frictionless)
A current $I$ flows along the length of an infinitely long, straight, thin-walled pipe. Then
$A= (1, -2, 3), B = (2, 1, 3), C = (4, 2, 1)$ and $G = (-1, 3, 5)$ is the centroid of the tetrahedron ABCD. If $p= D_y$ and $q = D_z$ then $ 13p-1.1q =$
A $0.5\, kg$ ball is thrown vertically up with $14 \,m s^{-1}$. It attains a height of $8\,m$. The energy dissipated by air drag acting on the ball during ascent is
A 1.0 mH inductance, a 10 $\mu F$ capacitance and a 5.0 ohm resistance are connected in series to an a.c. source. It is found that the inductor and the capacitor show equal reactances. The reactance should be nearest to
A $0.5\, dm^3$ flask contains gas $A$ and $1 \,dm^3$ flask contains gas $B$ at the same temperature. If density of $A = 3.0\, g\, dm^{-3}$ and that of $B = 1.5\, g\, dm^{-3}$ and the molar mass of $A=\frac{1}{2}$ of $B$, then the ratio of pressure exerted by gases is
A $0.2\, k\Omega$ resistor and $15\,\mu F$ capacitor are connected in series to a $220\,V$, $50\,Hz$ ac source. The impedance of the circuit is
Clouds appear to float in air due to
$^{}_{92}U^{238}$ on absorbing a neutron goes over to $^{}_{92}U^{239} .$ This nucleus emits an electron to go over to neptunium which on further emitting an electron goes over to plutonium. The resulting plutonium can be expressed as.
96500 C electricity is passed through $CuSO_4$. The amount of copper precipitated is
A small ball of density $\rho$ is immersed in a liquid of density $(\sigma > \rho)$ to a depth h and released. The height above the surface of water up to the ball will jump is
The S.I Unit of pressure is
If plane surface of a piano convex lens is silvered, then it will behave as a
A body is dropped from a height of $4 \,m$ on a surface. If in collision $25\%$ of energy is lost, then the height upto which it will rise after collision is
The relationship between Young's modulus $Y$, bulk modulus $K$ and modulus of rigidity $\eta$ is
8000 identical water drops combine together, to form a big drop. Then the ratio of the final surface energy to the initial surface energy of all the drops together is.
A closed iron ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet is
Longitudinal wave can travel in
The number of $\alpha$-particles and $\beta$-particles respectively emitted in the reaction $ {_{88}A^{196} -> _{78}B^{164}}$
$\left(^{8}C_{1} - ^{8}C_{2} + ^{8}C_{3} -^{8}C_{4} + ^{8}C_{5} - ^{8}C_{6} +^{8}C_{7} - ^{8}C_{8}\right) $ equals:
A projectile is projected with speed $49\,ms^{-1}$ at an angle of $30^{\circ}$ with horizontal. The time taken by the projectile to reach the highest point is