The ratio of the concentration of electrons to that of the holes in a semiconductor is 7/5 and the ratio of currents is 7/4. Then what is the ratio of their drift velocities?

What will be the input of A and B for the Boolean expression $$\overline{A+B}.\ \overline{A.B}$$ = 1?

Given below are four logic gates symbols. NAND, NOR and OR are respectively

The number of silicon atom per m3 is $$5\times10^{28}$$ . This is doped simultaneously with $$5\times10^{22}$$ atom per m3 of Arsenic and $$5\times10^{20}$$ atom per m3 of Indium. Then number of hole is $$n_h = 1.5\times10^{16} per m^3$$

An α-particle of energy 5 MeV is scattered through 180° by a fixed uranium nucleus. The distance of closest approach is of the order of:

In Rutherford’s experiment then number of alpha particles scattered through an angle of 90° is 28 per minute. Then the number of particles scattered through an angle of 60° per minute by the same nucleus is

If the binding energy of the electron in a hydrogen atom is 13.6eV, the energy required to remove the electron from the first excited state of Li++ is:

The radius of germanium (Ge) nuclide is measured to be twice the radius of 4Be^9. The number of nucleons in Ge are

An α-particle of energy bombards a heavy nuclear target of charge. The distance of closest approach for alpha particle will be proportional to

In Rutherford's scattering experiment what will be the correct angle for α scattering for an impact parameter b = 0?

What will be the number of photons emitted per second by a 10 watt sodium vapour lamp assuming that 90% of the consumed energy is converted into light (wavelength of sodium light is 590 nm)?

Work function of a metal is 4eV. The wavelength of incident radiation required just to emit the electrons from the surface is:

What is the de-Broglie wavelength associated with an electron accelerated through a potential difference of 100 volt?

The stopping potential for photoelectrons from a metal surface is V₁ when monochromatic light of frequency ν₁ is incident on it. The stopping potential becomes V₂ when monochromatic light of another frequency is incident on the same metal surface. If h be the planck's constant and e be the charge of an electron, then the frequency of light in the second case is

Monochromatic light of frequency 6 × 10¹⁴ Hz is produced by a laser. The power emitted is 2 × 10⁻³ W. The number of photons emitted on the average by the source per second is:

A source S₁ is producing 10¹⁵ photons per second of wavelength 5000 Å. Another source S₂ is producing photons per second of wavelength 5100 Å. Then (Power of S₁) / (Power of S₂) is equal to:

Ratio of intensities of two waves is given by 4 : 1. The ratio of the amplitudes of the waves is:

The amplitudes of two waves are in the ratio 1 : 4. The ratio of maximum to minimum intensity due to super position is

In a Fraunhoffer diffraction at a single slit of width d with incident light of wavelength 5500A°, the first minima is observed at an angle 30°. The first secondary maxima is observed at an angle θ equals

The Brewster's angle for the glass-air interface is 54.74°. If a ray of light going from air to glass strikes at an angle of incidence 45°, then the angle of refraction is

In a YDSE arrangement, slit separation is d=1mm, separation between screen and slit D=1m and wavelength used is 0.5mm. The separation between central maximum and first maximum on the screen is

White light is used to illuminate the two slits in YDSE. The separation between the slits is 'd' and the distance between the screen and the slit is D (D > d). At a point on the screen in front of one of the slits, certain wavelengths are missing.

A plano convex lens fits into exactly into a plano-concave lens. Their plane surfaces are parallel to each other. If lenses are made of different materials of refractive indices μ₁ and μ₂ and R is the radius of curvature of the curved surface of the lenses, then the focal length of combination is:

A thin double convex lens has radii of curvature each of magnitude 40 cm and is made of glass with refractive index 1.65. Its focal length is nearly:

A thin rod of length f/3 is placed along the principal axis of a concave mirror of focal length f, such that its image which is real and elongated, just touches the rod. The magnification is:

A point object is at a height x above the surface of water of refractive index 4/3 in a lake. A fish inside the lake observe the point object at a height 32 cm from the surface of water. The value of x is:

A concave mirror of focal length f1 is placed at a distance d from the convex lens of focal length f2. A beam of light coming from infinity and falling on this convex lens - concave mirror combination returns to infinity. The distance d must equal

Statement I: Focal length of an equiconvex lens placed in air is always equal to the radius of curvature of either face. Statement II: For an equiconvex lens the radius of curvature of both the surfaces is not same.

A plane EM wave travels in free space along X direction. If the value of B (in tesla) at a particular point in space and time is 1.2 × 10⁻⁸ k̂. The value of E (in Vm⁻¹) at that point is

An instantaneous displacement current of 2A can be established across 2μF capacitor, if the potential difference across the plates changes at the rate of

A radio wave of intensity 1 W/m^2 is absorbed by a surface. The pressure exerted on the surface is:

A point source of electromagnetic radiation has an average power output 800W. The maximum value of electric field at a distance 40 m from the source is

The magnetic flux through a circuit of resistance R changes by an amount Δϕ in a time Δt. Then the total quantity of electric charge Q that passes any point in the circuit during the time Δt is represented by

A coil of resistance 400Ω is placed in a magnetic field. If the magnetic flux ϕ (Wb) linked with the coil varies with time t (sec) as $$\phi = 50t^2 + 4$$ . The current in the coil at t = 2s is

An alternating voltage V = 20sin 50t + 40cos 50t is applied to a resistor of resistance 10Ω. The rms value of the current through the resistor is:

When a dc volt of 200 V is applied to a coil of self inductance (2√3/π) H, a current of 1A flows through it. But by replacing dc source with ac source of 200 V, the current in the coil is reduced to 0.5 A. The frequency of ac supply is:

The core of a transformer is laminated because:

A step-up transformer operates on a 230 V line and supplies current of 2 A to a load. The ratio of the primary and secondary windings is 1 : 25. The current in the primary coil is:

The mass of a ferromagnet material is 0.6kg and density 7.8 × 10³ Kg/m³. If area of hysteresis loop of alternating magnetising field of frequency 50Hz is 0.7 SI unit. The hysteresis loss per second will be:

When a rod of magnetic material of size 10 cm × 0.5cm × 0.2 cm is located in magnetising field of 0.5 × 10⁴ Am⁻¹, then a magnetic moment of 5 Am² is induced in it. The magnetic induction in rod is:

Ratio of intensity of magnetisation and magnetising field is called

At curies point a ferromagnetic material becomes

A magnet is parallel to a uniform magnetic field. It is rotated by 60°. The work done is 0.8J. How much work is done in moving it further 30°?

A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.25 T experiences a torque of magnitude equal to 4.5 × 10⁻² J. The magnitude of magnetic moment of the magnet is

In order to increase the sensitivity of a moving coil galvanometer, one should decrease

A moving coil galvanometer has a resistance of 900Ω. In order to send only 10% of the main current through the galvanometer, the resistance of the required shunt is

A positive charge is moving downward in a magnetic field which is towards north. The particle will be deflected towards

A proton and an α- particle moving with the same velocity enter into a uniform magnetic field, acting normal to the plane of their motion. The ratio of the radii of the circular paths described by the proton and α- particle is

A wire is stretched so that its radius is reduced to one-third of the original value. Find the ratio of final resistance to initial resistance

In a meter bridge experiment, the value of unknown resistance is 2Ω. To get the balancing point at 40 cm distance from the same end the resistance in the resistance box will be

At a certain distance from a point charge the electric field is 500 V/m and the potential is 3000V. What is the distance?

The ratio of force acting on an Alpha particle, if it is placed at a distance 'r' from the centre of a small electric dipole on the axial point to that on the equatorial point is:

A force of 2.25N acts on a charge of 15×10-4

C. Calculate the intensity of electric field at

the point

The ratio of minimum to maximum

capacitance of n equal capacitors in

combination is