List of practice Questions

A wheel is free to rotate about a horizontal axis through \( O \). A force of 200 N is applied at a point \( P_2 \) from the center \( O \). \( OP \) makes an angle of 55° with the \( x \)-axis and the force is in the plane of the wheel making an angle of 25° with the horizontal axis. What is the torque?
A hockey player hits the ball at an angle of 37° from the horizontal with an initial speed of 40 m/s (a right-angled triangle with one of the angles being 37° and their sides in the ratio of 6 : 8 : 10). Assume that the ball is in a vertical plane. The time at which the ball reaches the highest point of its path is:
What feature of the infrared waves make it useful for the haze photography?
A light having wavelength 6400 \( \text{\AA} \) is incident normally on a slit of width 2 mm. Then the linear width of the central maximum on the screen kept 2 m from the slit is:
What should be the inductance of an inductor connected to 200 V, 50 Hz source so that the maximum current of \( \sqrt{2} \, \text{A} \) flows through it?
The nucleus of a helium atom travels along the inside of a straight hollow tube 4 m long which forms part of a particle accelerator. If one assumes uniform acceleration, how long is the particle in the tube if it enters at a speed of 2000 m/s and leaves at 8000 m/s?

In the given circuit the diode \( D_1 \) and \( D_2 \) have the forward resistance 250 \(\Omega\) and infinite backward resistance. When they are connected to the source as shown, the current passing through the 175 \(\Omega\) resistor is:

The radius of the current carrying circular coil is doubled keeping the current passing through it the same. Then the ratio of the magnetic field produced at the centre of the coil before the doubling of the radius to the magnetic field after doubling of the radius is:
If the resultant of all external forces acting on a system of particles is zero, then from an inertial frame one can surely say that:
The reverse current in the semiconductor diode changes from 20 \(\mu\text{A}\) to 40 \(\mu\text{A}\) when the reverse potential is changed from 10 V to 15 V, then the reverse resistance of the junction diode will be:
The molecules of a given mass of a gas have root mean square speed of 120 m/s at 88°C and 1 atmospheric pressure. The root mean square speed of the molecules at 127°C and 2 atmospheric pressure is:
The acceleration due to gravity at a height of 7 km above the earth is the same as at a depth \( d \) below the surface of the earth. Then \( d \) is:
A tentative explanation of observations without assuming that it is true is called:
Find the pole strength of a magnet of length 2 cm, if the magnetic field strength \( B \) at distance 10 cm from the centre of a magnet on the axial line of the magnet is \( 10^{-4} \, \text{T} \).
In the head-on collision of two alpha particles \( \alpha_1 \) and \( \alpha_2 \) with the gold nucleus, the closest approaches are 31.4 fermi and 94.2 fermi respectively. Then the ratio of the energy possessed by the alpha particles \( \alpha_2 / \alpha_1 \) is:
Two black bodies P and Q have equal surface areas and are kept at temperatures \( 127^\circ C \) and \( 27^\circ C \) respectively. The ratio of thermal power radiated by A to that by B is:
The SI unit of electrical conductivity is:
The ground state energy of hydrogen atom is -13.6 eV. If the electron jumps from the 3rd excited state to the ground state, then the energy of the radiation emitted will be:
In the Young's double slit experiment the fringe width of the interference pattern is found to be \(3.2 \times 10^{-4}\) m, when the light of wavelength 6400 \(\text{Å}\) is use(D) What will be the change in fringe width if the light is replaced with a light of wavelength 4800 \(\text{Å}\)?
What will be the change in wave length, if a light of wave length 600 nm travels from air enters a medium of refractive index 1.5 and continues its journey through that medium?
A resistor of wire 24 cm length and resistance 8Ω is stretched into a uniform wire of 48 cm length, then the new resistance will be:
A metallic rod of 10 cm is rotated with a frequency 100 revolution per second about an axis perpendicular to its length and passing through its one end in a uniform transverse magnetic field of strength 1 T. The emf developed across its ends is:
Two open organ pipes A and B of length 22 cm and 22.5 cm respectively produce 2 beats per sec when sounded together. The frequency of the shorter pipe is:
The time dependence of a physical quantity \(P\) is given by \[ P = P_0 \exp(-\alpha t^2) \] where \(\alpha\) is a constant and \(t\) is time. The constant \(\alpha\) will:
The electric flux from a cube of side 1 m is \(\Phi\). When the side of the cube is made 3 m and the charge enclosed by the cube is made one-third of the original value, then the flux from the bigger cube will be: