JEE Main Practice Test- 18 - JEE MCQ

Which of the following is true?

A car is moving in a circular horizontal track of radius 10 m with a constant speed of 10 m/sec. A plump bob is suspended from the roof of the car by a light rigid rod of length 1.00 m. The angle made by the rod with track is

The approximated wavelength of a photon of energy 2.48eV is

A point Q lies on the perpendicular bisector of an electrical dipole of dipole moment p. If the distance of Q from the dipole is r (much larger than the size of the dipole), then the electric field at Q is proportional to :

The electric field at the centroid of an equilateral triangle carrying an equal charge q at each of the vertices is

A lift of mass 1000 kg is moving with an acceleration of 1 m−s⁻² in upward direction. Tension developed in the string, which is connected to the lift, is

A machine gun fires a bullet of mass 40 g with a velocity 1200 m−s⁻1. The man holding it can exert a maximum force of 144 N on the gun. How many bullets can he fire per second at the most?

A long solenoid has n turns per metre and current I ampere is flowing through it. The magnetic field at the ends of solenoid is

The logic behind 'NOR' gate is that, it gives

Two pieces of a glass plate, placed one upon the other with a little water in between them, can not be separated easily, because of

The function of the moderator in a nuclear reactor is

The sum of two vectors A → and B → is at right angles to their difference. Then

In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A):In a nuclear reactor cadmium acts as a moderator.
Reason(R):The cadium rods are so inserted in the graphite block so that they can be slided in and out as per requirement.

In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Energy density in the solenoid is greater at centre than near its ends.
Reason(R): Energy density is defined as 

A solid cylinder of mass M and radius R rolls down an inclined plane without slipping. The speed of its centre of mass when it reaches the bottom is

There are two lead spheres at the same temperature, the ratio of radii being 1:2 The ratio of head capacities are

For the constructive interference the path difference between the two interfering waves must be equal to

The fundamental unit which has the same power in the dimensional formula of surface tension and viscosity is

If a star is moving towards earth, then the lines are shifted towards

A parallel monochromatic beam of light is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the first minimum of the diffraction pattern, the phase difference between the rays coming from the two edges of slit is

When a tuning fork of frequency 341 is sounded with another tuning fork, six beats per second are heard. When the second tuning fork is loaded with wax and sounded with the first tuning fork, the number of beats is two per second. The natural frequency of the second tuning fork is

d/dx [tan^-1 cosx/(1 + sin x)] =

Singly ionized helium (He⁺) atom is hydrogen like in the sense that a solitary electron revolves around a positively charged nucleus. If the energy of this electron in its first orbit (n = 1) is -54.4 eV, what will be its energy in the first excited state?

The charge deposited on 4 μ F capacitor in the circuit is

The angular velocity of the second needle in watch (in rad/s) is

We are able to obtain fairly large currents in a conductor because

A charge +4q is located on the X-axis of a Cartesian coordinate system at x = -2a as shown. Another charge +(q/4) is located on the X-axis at x = a. Where on the Y-axis should a third charge -3q be placed so that the resultant electric field at the origin O has equal positive X and Y components?