Physics Mock Test-3

Planck’s constant has same dimensions as those of

The dimensions of pressure are equal to those of

A step down transformer is used on a 1000 V line to deliver 20 A at 120 V at the secondary coil. If the efficiency of the transformer is 80%, the current drawn from the line is

₆C¹⁴ absorbs an energitic neutron and emits beta particles. The resulting nucleus is

A 1m long wire of diameter 0.31 mm has a resistance of 4.2Ω. If it is replaced by another wire of same material of length 1.5m and diameter 0.155 mm, then the resistance of wire is

A certain current on passing through a galvanometer produces a deflection of 100 divisions. When a shunt of one ohm is connected, the deflection reduces to division. The galvanometer resistance is

An electron is

A and B are two metals with threshold frequencies 1.8 x 10¹⁴ Hz and 2.2 x 10¹⁴ Hz. Two identical photons of energy 0.825 eV each are incident on them. Then photoelectrons are emitted in (Take h=6.6 x 10³⁴ Js)

The energy of groundstate (n=1) of hydrogen level is -13.6 eV. The ionistation potential of the hydrogen atom is

A device which converts electrical energy into mechanical energy is

A coil of inductive reactance 31 Ω has a resistance of 8 Ω. It is placed in series with a condenser of capacitative reactance 25 Ω. The combination is connected to an a.c. source of 110 V. The power factor of the circuit is

In case of linearly polarised light, the magnitude of the electric field vector

Which gate can be obtained by shorting both the input terminals of a NOR gate?

Pure Si at 300 k has equal electrons (nₑ) and hole (nh) concentrations of 1.5×10⁺¹⁶ m⁻³. Dopping by indium, nh increases to 3×10²² m⁻³. What is nₑ in doped Si?

A battery charges a parallel plate capacitor seperated by distance(d) so that the energy (V₀) is stored in the system. A slap of dielectric constant (K) and thickness(d) is then introduced between the plates of capacitor. The new energy of the system is given by

A particle of mass 1.96×10⁻¹⁵ kg is kept in equilibrium between two horizontal metal plates having potential difference of 400V seperated apart by 0.02m. Then the charge on the particle is (e=electronic charge)

A satellite A of mass m is at a distance r from the centre of earth. Another satellite B of mass 2m is at a distance 2r from the earth centre. Their time periods are in the ratio of

If R is the radius of earth, the height at which the weight of a body 1/4 of its weight on the surface of earth.

Two springs with spring constants K₁=1500 N/m and K₂=3000 N/m are stretched by the same force. The ratio of potential energy stored in springs will be

A block of mass 5 kg is moving horizontally at a speed of 1.5 m/s. A perpendicular force of 5 N acts on it for 4 sec. What will be the distance of the block from the point where the force started acting?

A bar magnet has a coercivity of 4×10³ Am⁻¹. It is placed inside a solenoid of length 12 cm having 60 turns in order to demagnetise it. The amount of current that should be passed through the solenoid is

A charged particle enters a uniform magnetic field with a certain speed at right angles to it. In the magnetic field a change could occur in its

An object is projected with a velocity of 20 m/s making an angle of 45⁰ with horizontal. The equation for the trajectory is h=Ax-Bx² where h is the height, x is the horizontal distance, A and B are constants. The ratio of A:B is (g=10 ms⁻²)

A particle of mass m moves with constant speed along a circular path of radius r under the action of a force F. Its speed is

Two bullets are fired simultaneously, horizontally and with different speeds from the same place. Which bullet will hit the ground first?

Two bodies A(of mass 1 kg) and B(of mass 3 kg) are dropped from heights of 16 m and 25 m, respectively. The ratio of the time taken by them to reach the ground is

A uniform rod of length l is placed with one end in contact with the horizontal and is then inclined at an angle α to the horizontal and allowed to fall, without slipping at contact point. When it becomes horizontal, its angular velocity will be

A circular disc of radius R and thickness R/6 has moment of inertia I about an axis passing through its centre and perpendicular to tis plane. It is melted and recasted into a solid sphere. The moment of inertia of the sphere about its diameter as axis of rotation is

A simple pendulum has a time period T₁ when on the earth’s surface and T₂ When taken to a height R above the earth’s surface where R is the radius of the earth. The value of T₂/T₁ is

An ideal spring with spring constant K is hung from the ceiling and a block of mass M is attached to its lower end. The mass is released with the spring initially unstretched. Then the maximum extension in the spring

A body undergoes no change in volume. Poisson’s ratio is

The respective speeds of the molecules are 1,2,3,4 and 5 km/s. The ratio of their r.m.s. velocity and the average velocity will be

If a nucleus ᴢXᴬ emits 9α and 5β-particles, then the ratio of total protons and neutrons in the final nucleus is

A radioactive substance decays to 1/16th of its initial activity in 40 days. The half-life of the radioactive substance expressed in days is

If critical angle for a material to air passage is 30°, the refractive index of the material will be

Aperture of human eye is 0.2 cm. The minimum magnifying power of a visual telescope, whose objective has diameter 100 cm is

The sun light reaches us as white and not as its components because

A carnot engine working between 300 K and 600 K has a work output of 800J per cycle. The amount of heat energy supplied to the engine from the source in each cycle is

During an adiabatic process, the cube of the pressure is found to be inversely proportional to the fourth power of the volume. Then the ratio of specific heats is

A plane wave of wavelength 6250Å is incident normally on a slit of width 2×10⁻² cm. The width of the principal maximum of diffraction pattern on a screen at a distance of 50cm will be

In Young’s double slit experiment, the ratio of maximum and minimum intensities in the fringe system is 9:1. The ratio of amplitudes of coherent sources is

If wavelength of a wave is λ=6000 Å, then wave number will be

A sound absorber attenuates the sound level by 20 dB. The intensity decreases by a factor of

A spring when stretched by 2mm containing energy 4 J. If it is stretched by 10 mm, its potential energy becomes equal to

A shell of mass 200 gm is ejected from a gun of mass 4 kg by an explosion that generates 1.05 kJ of energy. The initial velocity of the shell is