A photon of energy 2.5eV and wavelength λ falls on a metal surface and the ejected electrons have a velocity 'V' . If the wave length λ of incident light is decreased by 20%, the velocity of emitted electrons is doubled, then the work function of the metal is
Two wires of same material have length L and 2L and cross-sectional areas 4A and A respectively. The ratio of their specific resistance would be
Find current i3 and find r
Which of the following relations is true ?
In an induction coil with resistance, the induced emf will be maximum, when
If the force on a rocket moving with a velocity of 300 m/s is 210 N, then the rate of combustion of fuel is
The electrical conductivity of the earth's atmosphere increases with altitude due to
Two satellites of earth, S1 and S2 moving in the same orbit. The mass of S1 is four times the mass of S2. Which one of the following statements is true?
Two small balls having equal positive charge q coulomb are suspended by two insulating string of equal length l metre from a hook fixed to a stand. The whole set up is taken in a satellite into space where there is no gravity. The tension in each string is
Two ions having equal masses but charges in the ratio 1:2 are projected perpendicular to a uniform magnetic field with speeds in the ratio 2:3. The ratio of the radii of the circular paths along which the two ions move is
An α -particle of mass 6.4 x 10−27 kg and charge 3.2 x 10−19C is situated in a uniform electric field of 1.6 x 105V m−1 . The velocity of the particle at the end of 2 x 10−2 m path when it starts from rest is
When 2 A current is passed through the coil of a tangent galvanometer, it gives a deflection of 45º. For 60º deflection, the current must be
The horizontal range of a projectile is R, when the angle of projection is 30º. The value of another angle of projection, for the same range, is
A weightless thread can support tension upto 30 N. A stone of mass 0.5 kg is tied to it and is revolved in a circular path of radius 2 m in a vertical plane. If g = 10 m/s2, then the maximum angular velocity of the stone will be
At what speed, the velocity head of water is equal to pressure head of 40 cm of Hg ?
The function of the moderator in a nuclear reactor is
A point initially at rest moves along x-axis. Its acceleration varies with time as a = (6t + 5)m/s2. If it starts from origin, the distance covered in 2 s is
The length of simple pendulum executing SHM is increased by 21%. The percentage increase in the time period of the pendulum of increased length is
Two simple pendulums of length 0.5 m and 20 m respectively are given small linear displacement in one direction at the same time. They will again be in the phase when the pendulum of shorter length has completed... oscillations
The angle subtended by a coin of radius 1 cm held at a distance of 80 cm from your eyes is
A body is rotating with angular velocity 30 rad/s. If its kinetic energy is 360 J, then its moment of inertia is
A child swinging ona swing in sitting position stands up. The time period of the swing will
In semi-conductor with the increase in temperature its resistance
On increasing the reverse bias to a large value in a P-N junction diode, current
540 g of ice at 0ºC is mixed with 540 g of water at 80ºC. The final temp. of the mixture in ºC will be
Which of the following parameters does not characterise the thermodynamic state of matter?
In C.G.S. system the magnitude of the force is 100 dynes. In another system where the fundamental physical quantities are kilogram, metre and minute, the magnitude of the force is
Vector 2i+aj+k is perpendicular to vector 2i-j-k if a=
The golden view of sea shell is due to
A body of mass m₁ is moving with a velocity V. it collides with another stationary body of mass m₂. They get embedded at the point of collision, the velocity of the system
A body of mass m = 3.513 kg is moving along the x-axis with a speed of 500 ms⁻1. The magnitude of its momentum is recorded as
To have a uniform electric field
The total current flowing in the given circuit is
Hail storms are observed to strike the surface of the frozen lake at 30º with the vertical and rebound at 60º with the vertical. Assume contact to be smooth, the coefficient of restitution is
A transparent solid cylindrical rod has a refractive index of It is surrounded by air. A light ray is incident at the midpoint of one end of the rod as shown in the figure.
The incident angle θ for which the light ray grazes along the wall of the rod is -
In Bohr's model of the hydrogen atom
A wave on a string passes the point x = 0 with amplitude A, angular frequency f, and average power P. As the wave travels down the string it gradually loses energy. At the point x = 1, the average power is then at x = 1,
The displacement of an oscillating particle is given by the equation x = a sinωt + b cosωt where a and b are constants
A rectangular block of mass m, area of cross section A floats in a liquid of density ρ . If it is given a small vertical displacement, it oscillates with a period T.
Which of the following form(s) a virtual and erect image for all positions of the object ?