Physics Test - ...

A boat capable of a speed v in still water wants to cross a river of width d. The speed of the water current increases linearly from zero at either bank to a maximum of u at the middle of the river. When the boat is rowed at right angles to the bank, its downstream drift is

The escape velocity for an atmospheric particle 2000 km above the earth’s surface is (Radius of the earth = 6.4 × 10⁶ m and g = 10 ms^{− 2} )

Four identical hollow cylindrical columns of steel, support a big structure of mass 60,000 kg. The inner and outer radii of each column are 40 cm and 50 cm respectively. When the load distribution is uniform, the compressional strain on each column is (Young’s modulus of steel is 2 × 10¹¹ Pa)

Two sources of sound S₁ and S₂ each emitting waves of wavelength λ are kept symmetrically on either side of the centre O of a circle ABCD such that S₁O = S₂O = λ. When the detector is moved along the circumference of the circle, the number of maxima recorded by the detector in one revolution is

A reversible heat engine converts one fourth of heat input into work. When the temperature of the sink is reduced by 200 K, its efficiency is doubled. The temperature of the source is

A square metal wire loop of side 20 cm and resistance 1 Ω is moved with a constant velocity v₀ in a uniform magnetic field of induction B = 4 Wb/m². The magnetic field lines are perpendicular to the plane of the loop and directed inwards. The loop is connected to a network of resistors each of value 2 Ω. The resistance of load wires AB and CD are negligible. To get a current of 2 mA in the loop, the speed of motion of the loop is

The walls of a closed cubical box of edge 50 cm are made of a material of thickness 1 mm and coefficient of thermal conductivity 4 × 10^{− 4} cal/s/cm/ °C. The interior of the box is maintained at 100 °C above the outside temperature by a heater placed inside the box and connected across 400 V d.c. The resistance of the heater is

In nuclear reaction, energy released per fission is 200 MeV. When uranium 235 is used as nuclear fuel in a reactor having a power level of 1 MW, the amount of fuel needed in 30 days will be

In the given circuit, V_CE = 30 V, V_BB = 20 V, R_B = 1 MΩ, R_C = 10 kΩ. Neglecting V_BE and taking β = 50, the values of I_C and I_E are respectively