Part Test- 7 (JEE Main 2018) - JEE MCQ

A small particle is placed over a sphere of radius R. It leaves the sphere at
______from top if it starts sliding 

A rod of length l is clamped to axis of rotation. A string of length l is tied at one end and a mass m
at the other as shown. Find angular velocity such that the string makes an angle ? with vertical

A block of mass M moving with velocity v hits another block at rest connected to a spring of spring
constant k. The maximum compression of the spring is (collision is perfectly inelastic)

Four spheres each of mass m and radius r are fixed at the vertices of a square (skelton) of side a.
It is rotated about side AB. The MOI is

Points A, B and C are marked as shown on a wheel rolling without slipping with angular velocity ω. Then

A uniform rod of length L and mass M lies on a frictionless table is free to move on the table. A particle of mass m moving with velocity u collides elastically with the rod at a distance L/3 from its centre and comes to rest immediately after collision. The ratio M/m is.

Two conducting balls each of mass 15 gm and having equal charge on them of 126 μC are suspended by two 1 m long silk threads as shown. The separation between them is 8 cm when they are in equilibrium. When one of the balls is discharged to have half the original charge on each the new equilibrium separation will be –

Two point charges Q and  are separated by L then which wrong -

One of the plates of a plane capacitor is suspended from the beam of a balance. The distance
between the capacitor plates is d = 5 mm and area of plates is 628 cm². What is the potential
difference between the capacitor plates if a weight of 1 gram has to be placed on the other pan of
the balance to obtain equilibrium –

In the circuit shown, C₁ = C₂ = 2 μF. Capacitor C₁ is charged to 50 volt and C₂ is charged to 20 volt. After charging they are connected as shown. When S₁, S₂ and S₃ are closed –

A charged particle moves undeflected in a region of electric and magnetic field. If the electric field is switched off, the particle has an initial acceleration a. If magnetic field is switched off, instead of electric field, the particle will have an initial acceleration -

In the circuit shown, sliding contact  is moving with uniform velocity towards right. Its value at some instance is 12. The current in the circuit in the circuit at this instant of time will be –

Magnitude of induced emf produced in a coil when a magnet is inserted into it, depends not on the-

When current in the circuit shown is 2A and is increasing at the rate of 1 A/S, the measured
potential difference between A and B is 16V. However when the current is 2A and is decreasing at
the rate of 1 A/S the measured potential difference between A and B is 8V

Switch S is closed at t = 0. If e denote the induced emf in L and i, the current flowing through
circuit at time t, which of the following graphs is wrong ?

A small particle of mass m moves in such a way that the potential energy   where ω is a constant and r is the distance of the particle from the origin. Assuming Bohr’s model of quantization
of angular momentum and circular orbits. The radius of nth allowed orbit is proportional to -

The potential energy of a particle of mass m is given by  λ₁ and λ₂ are the de-Broglie wavelength of the particle when 0 x 1 and x > 1 respectively if the
total energy of the particle is 2E₀ the ratio of λ₁ / λ₂ will be -

The de-broglie wavelength of the electron in the second Bohr orbit is (given the radius of the first
orbit  

A sonometer wire resonates with a given tuning fork forming standing waves with five antinodes
between the two bridges when a mass of 9 kg. is suspended from the wire. When this mass is
replaced by a mass M, the wire resonates with the same tuning fork forming three antinodes for the
same positions of the bridges. The value of M is -

A sonometer wire is 31cm long is in resonance with a tuning fork of frequency n. If the length is
increased by 1cm and it is vibrated with the same tuning fork, then 8 beats/sec are heard. The
frequency of the tuning fork is -

Two whistles A and B produce notes of frequencies 660 Hz and 596 Hz respectively. There is a
listener at the midpoint of the line joining them. Both the whistle B and the listener start moving
with speed 30 m/s away from whistle A. If speed of sound be 330 m/s, how many beats will be heard
by the listener ?

The graph in figure shows how the inverse of magnification 1/m produced by a convex thin lens varies with object distance u. What was the focal length of the lens used ?

The effective focal length of the lens combination shown in the figur is – 60 cm. The radii of curvature of the curved surfaces of the plano- convex lenses are 12 cm each and refractive index of the material of the lens is 1.5. The refractive index of the liquid is:

Two coherent sources of intensity ratio β interfere. Then the value of (I_max – I_min)/(I_max + I_min) is:

In Young’s double slit experiment, white light is used. The separation between the slits is b. The screen
is at a distance d(d >> b) from the slits. Some wavelengths are mission exactly in front of one slit.
These wavelengths are:

In a double slit experiment, the distance between the slits is d. The screen is at a distance D from
the slits. If a bright fringe is formed opposite of one of the slits, find its order :

Two wavelengths of light λ₁ and λ₂ are sent through Young’s double slit apparatus simultaneously.
What must be true about λ₁ and λ₂ if the third order bright fringe of λ₁ coincides with fifth order dark
fringe of λ₂ ?