Physics Mock Test-6

The unit of reactance is

The physical quantities not having same dimensions are

A capacitor of 2.5 μF is charged through a resistor of 4 MΩ. In how much time will potential drop across capacitor will become 3 times that of resistor (ln2=0.693)

A galvanometer of resistance 50Ω is connected to a battery of 3 V along with a resistance of 2950 Ω in series. A full scale deflection of 30 divisions is obtained in the galvanometer. In order to reduce this deflection to 20 divisions, the resistance in series should be

An atom bomb works on the principle of

A gas of monoatomic hydrogen is bombarded with a stream of electrons that have been accelerated from rest through a potential difference of 12.75 volt. In the emission spectrum one can observe lines of

The de-broglie wavelength of an electron in 4th orbit is ( where, r= radius of 1st orbit)

A DC ammeter has resistance 0.1Ω and its current ranges 0-100A. If the range is to be extended to 1-500, then the following shunt resistance will be required

A 50 ohm galvanometer gets full scale deflection when a current of 0.01 A passes through the coil. When it is converted into a 10 A ammeter, the shunt resistance is

Bragg’s law for X-rays is

A light of wavelength 5000Å falls on a sensitive plate with photoelectric work function 1.90 eV. Kinetic energy of the emitted photoelectrons will be (given, h=6.62×10⁻³⁴ Js)

A solenoid of length l metre has self inductance L henry. If number of turns are doubled, its self inductance

Electromagnetic induction is not used in

An amplifier has a voltage gain Av=1000. The voltage gain in dB is

The necessary condition in making of a junction transistor (E- emitter, B- base and C- collector)

A capacitor is used to store 24 watt hour of energy at 1200 volt. What should be the capacitance of the capacitor?

A gaussian sphere encloses an electric dipole within it. The total flux across the sphere is

Imagine a new planet having the same density as that of earth but it is 3 times bigger than the earth in size. If the acceleration due to gravity on the surface of earth is g and that on the surface of the new planet is g’, then

A satellite is revolving around the earth with a kinetic energy E. The minimum addition of kinetic energy needed to make it escape from its orbit is

A marble block of mass 2 kg lying on ice when given a velocity of 6 m/s is stopped by friction in 10 sec. Then the coefficient of friction is

A 0.5 kg ball moving with a speed of 12 m/s strikes a hard wall at an angle of 30° with the wall. It is reflected with the same speed at the same angle. If the ball is in contact with the wall for 0.25 seconds, the average force acting on the wall is

A charged particle with a velocity 2×10³ ms⁻¹ passes undeflected through electric field and magnetic fields in mutually perpendicular directions. The magnetic field is 1.5T. The magnitude of electric field will be

At which place, Earth’s magnetism becomes horizontal

If two bodies are projected at 30⁰ and 60⁰ respectively with the same velocity, then

The coefficient of friction between the tyres and the road is 0.25. The maximum speed with which a car can be driven round a curve of radius 40 m without skidding is (assume g=10 ms⁻²)

A body covers 200 cm in the first 2 seconds and 220 cm in the next 4 seconds. The velocity of the body at the end of the 7th second is

A particle starting from the origin (0,0) moves in a straight line in the (x,y) plane. Its coordinates at a later time are (√3,3). The path of the particles makes with the x-axis an angle of

Two solid discs of radii r and 2r roll from the top of an inclined plane without slipping. Then

The moment of inertia of a uniform circular disc of radius R and mass M about an axis touching the disc at its diameter and normal to the disc

The escape velocity of a body on an imaginary planet which is thrice the radius of the earth are double the mass of the earth (Ve is the escape velocity from the earth)

The period of a simple pendulum inside a stationary lift is T. The lift accelerates upwards with an acceleration of g/3. The time period of pendulum will be

A body cools in 7 minute from 60⁰C to 40⁰C. What time, in minute does it take to cool from 40⁰C to 28⁰C if the surrounding temperature is 10⁰C? Assume Newton’s law of cooling

A wooden stick 2 m long is floating on the surface of water. The surface tension of water is 0.07 N/m. By putting soap solution on one side of the sticks, the surface tension is reduced to 0.06 N/m. The net force on the stick will be

A uranium nucleus ₉₂ U ²³⁸ emits an α-particle and a β-particle in succession. The atomic number and mass number of the final nucleus will be

A radioactive substance emits n beta particles in the first 2 s and 0.5 n beta particles in the next 2 s. The mean life of the sample is

The magnifying power of a convex lens of focal length 10 cm, when the image is formed at the near point is

If the focal length of a concave mirror is 50 cm, then where should the object is placed, so that its image is two times and inverted

A monoatomic gas is suddenly compressed to (1/8)th of its initial volume adiabatically. The ratio of its final pressure to the initial pressure is (given the ratio of the specific heat of the given gas to be 5/3)

An ideal gas is expanding such that PT²=constant. The coefficient of volume expansion of the gas is

A beam of light contains two wavelengths 6500Å and 5200Å. They form interference fringes in Young’s double slit experiment. What is the least distance (approx) from central maximum, where the bright fringes due to both wavelength coincide? The distance between the slits is 2 mm and the distance of screen is 120 cm.

The parallel beams of monochromatic light of wavelength 4.5 x10⁻⁷ m passes through a long slit with width 0.2×10⁻³ m. The angular divergence in which most of the light is

If the length of a closed organ pipe is 1.5 m and velocity of sound is 330 m/s, then the frequency for the second note is

A sound source is moving towards a stationary listener with 1/10th of the speed of sound. The ratio of apparent to real frequency is

A bomb of mass 16 kg at rest explodes into two pieces of masses of 4 kg and 12 kg. The velocity of the 12 kg mass is 4 ms⁻¹. The kinetic energy of the other mass is

A uniform chain of length L and mass m is kept on a smooth table. It is released from rest when the overhanging part was nᵗʰ fraction of total length. Find the kinetic energy of the chain as it completely slips off the table