Physics Mock Test-4

Unit of electrical conductivity is

Which of the two have same dimensions?

A galvanometer coil has a resistance of 15 ohm and gives full-scale deflection for a current of 4 mA. To convert it to an ammeter of range 0 to 6 A,

According to Bohr model of hydrogen atom, only those orbits are permissible which satisfy the condition

The wavelength of kα, X-rays produced by an X-ray tube 0.76Å. The atomic number of the anode material of the tube is

A 1Ω resistance in series with an ammeter is balanced by 75 cm of potentiometer wire. A standard cell of emf 1.02 V is balanced by 50 cm. The ammeter shows a reading of 1.5A. Then, the error in ammeter reading is

A metal plate weighing 750g is to be electroplated with 0.05% of its weight of silver. If a current of 0.8A is used, find the time (approx) needed for depositing the required weight of silver (ECE of silver is 11.8×10⁻⁷kgC⁻¹)

Three resistances 2Ω, 3Ω and 4Ω are connected in parallel. The ratio of currents passing through them when a potential difference is applied across its ends will be

An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is

In a laser tube, all the photons

Electrons in a certain energy level n=n₁, can emit 3 spectral lines. When they are in another energy level, n=n₂. They can emit 6 spectral lines. The orbital speed of the electrons in the two orbits are in the ratio

A coil of N turns and mean cross-sectional area A is rotating with uniform angular speed ω about an axis at right angle to uniform magnetic field B. The induced e.m.f. E in the coil will be

A horizontal straight conductor kept in north-south direction falls under gravity. Then

A common emitter amplifier is designed with n-p-n transistor (α=0.99). The input impedence is 1kΩ and load is 10kΩ. The voltage gain will be

A tuned amplifier circuit is used to generate a carrier frequency of 2 MHz for the amplitude modulation. The value of √(LC) is

A capacitor having a capacity of 2 μF is charged to 200V and then the plates of the capacitor are connected to a resistance wire. The heat produced in joule will be

A cylindrical capacitors has charge Q and length L. If both the charge and length of the capacitors are doubled, by keeping other parameters fixed, the energy stored in the capacitor

A satellite in a circular orbit of radius R has a period of 4 hours. Another satellite with orbital radius 3R around the same planet will have a period (in hours)

The escape velocity of a body from earth’s surface is Ve. The escape velocity of the same body from a height equal to 7R from earth’s surface will be

A force of 10 newton acts on a body of mass 20 kg for 10 seconds. Change in its momentum is

The vector sum of two forces is perpendicular to their vector difference. In that case, the forces

A charged particle experiences magnetic force in the presence of magnetic field. Which of the following statement is correct?

A current I ampere flows along the inner conductor of a co-axial cable and returns along the outer conductor of the cable, then the magnetic induction at any point outside the conductor at a distance r metre from the axis is

A cycle wheel of radius 4 m completes one revolution in two seconds. Then acceleration of cycle will be

A particle moves with constant speed v along a circular path of radius r and completes the circle in time T. The acceleration of the particle is

A body moves with a uniform acceleration a and zero initial velocity. Another body B starts from the same point moves in the same direction with a constant velocity v. The two bodies meet after a time t. The value of t is

The friction of the air causes a vertical retardation equal to 10% of the acceleration due to gravity (take g=10 ms⁻²). The maximum height will be decreased by

Two rigid bodies A and B rotate with rotational kinetic energies Eᴀ and Eʙ respectively. The moments of inertia of A and B about the axis of rotation are Iᴀ and Iʙ respectively. If Iᴀ = (Iʙ/4) and Eᴀ = 100 Eʙ, the ratio of angular momentum (Lᴀ) of A to the angular momentum (Lʙ) of B is

A meter stick of mass 400 g is pivoted at one end and displaced through an angle 60°. The increase in its potential energy is

The acceleration due to gravity at a place is π² m/sec². Then the time period of a simple pendulum of length one metre is

If angular momentum of a body is increased by 200% its kinetic energy will increase by

Minimum and maximum values of Poisson’s ratio for a metal lies between

Two bodies A and B having temperature 327° C and 427° C are radiating heat to the surroundings. The surrounding temperature is 27°C. The ratio of rate of heat radiation of A to that of B is

The half-life of a radioactive substance is 30 min. The time (in minutes) taken between 40% decay and 85% decay of the same radioactive substance is

A nucleus disintegrates into two nuclear parts which have their velocities in the ratio 2 : 1. The ratio of their nuclear sizes will be

The velocity of image when object and mirror both are moving towards each other with velocities 4 ms⁻¹ and 5 ms⁻¹ respectively, is

A concave lens of focal length f forms an image which is 1/3 times the size of the object. Then, the distance of object from the lens is

The coefficient of performance of a Carnot refrigerator working between 30⁰C and 0⁰C is

40 g of Argon is heated from 40⁰C to 100⁰C (R=2 cal/mole). Heat absorbed at constant volume is

The polarising angle of glass is 57⁰. A ray of light which is incident at this angle will have an angle of refraction as

In Young’s double slit interference experiment, using two coherent waves of different amplitudes, the intensities ratio between bright and dark fringes is 3. Then, the value of the wave amplitudes ratio heat arrive there is

A string is stretched between fixed points separated by 75 cm. It is observed to have resonant frequencies of 420 Hz and 315 Hz. There are no other resonant frequencies between these two. Then, the lowest resonant frequency for this string is

A vibrating string of certain length l under a tension T resonates with a mode corresponding to the first overtone (third harmonic) of an air column of length 75 cm inside a tube closed at one end. The string also generates 4 beats per second when excited along with a tuning fork of frequency n. Now when the tension of the string is slightly increased the number of beats reduces to 2 per second. Assuming the velocity of sound in air to be 340 m/s, the frequency n of the tuning fork in Hz is

If a body is rolling on the surface, its total energy will be

In the elastic collision of objects