JEE Main entrance exam Question Bank Solutions for Physics (JEE Main)

In the wave equation

`y = 0.5sin  (2pi)/lambda(400t - x)m`

the velocity of the wave will be ______.

A transverse wave is represented by y = 2sin (ωt - kx) cm. The value of wavelength (in cm) for which the wave velocity becomes equal to the maximum particle velocity, will be ______.

A small speaker delivers 2W of audio output. At what distance from the speaker will one detect 120 dB intensity sound?

[Given reference intensity of sound as 10^-12W/m²]

Two stars of masses m and 2m at a distance d rotate about their common centre of mass in free space. The period of revolution is ______.

A hydraulic press can lift 100 kg when a mass 'm' is placed on the smaller piston. It can lift ______ kg when the diameter of the larger piston is increased by 4 times and that of the smaller piston is decreased by 4 times keeping the same mass 'm' on the smaller piston.

The resistance R = `"V"/"I"`, where V = (50 ± 2) V and I = (20 ± 0.2)A. The percentage error in R is 'x' %. 

The value of x to the nearest integer is ______.

In a Screw Gauge, the fifth division of the circular scale coincides with the reference line when the ratchet is closed. There are 50 divisions on the circular scale, and the main scale moves by 0.5 mm on a complete rotation. For a particular observation, the reading on the main scale is 5 mm and the 20^th division of the circular scale coincides with the reference line. Calculate the true reading.

In a reactor, 2 kg of ₉₂U²³⁵ fuel is fully used up in 30 days. The energy released per fission is 200 Me V given that the Avogadro number, N = 6.023 × 10²⁶ per kilo mole and 1 eV = 1.6 × 10^-19 J. The power output of the reactor is close to :

A long string, having a cross-sectional area 0.80 mm² and density 12.5 g/cm³ is subjected to a tension of 64 N along the x-axis. One end of the string is attached to a vibrator moving in transverse direction. At t = 0, the source is at maximum displacement y = 1 cm. Find the speed of wave travelling on the string.

The dependence of g on geographical latitude at sea level is given by `g = g_0(1 + betasin^2Phi)` where Φ is the latitude angle and β is a dimensionless constant. If Δg is the error in the measurement of g then the error in measurement of latitude angle is ______.

The greatest speed of transverse waves through a steel wire of radius 1 mm is ______ × 10² m. The breaking stress of steel is 6.0 × 10⁸ Nm^-2. Density of steel = 7800 kg m^-3.

Two light beams of intensities in the ratio of 9 : 4 are allowed to interfere. The ratio of the intensity of maxima and minima ______.

A travelling microscope has 20 divisions per cm on the main scale while its Vernier scale has total 50 divisions and 25 Vernier scale divisions are equal to 24 main scale divisions, what is the least count of the travelling microscope?

A travelling microscope is used to determine the refractive index of a glass slab. If 40 divisions are there in 1 cm on main scale and 50 Vernier scale divisions are equal to 49 main scale divisions, then least count of the travelling microscope is ______ × 10^-6 m. 

The least count of the main scale of a screw gauge is 1 mm. The minimun number of divisions on its circular scale required to measure 5 µm diameter of a wire is ______.

If the zero of the vernier lies on the right-hand side and the fourth division coincides with the main scale division when the jaws are in contact so the correction will be ______.

The radius in kilometers to which the present radius of the earth (R = 6400 km) is to be compressed so that the escape velocity is increased 10 times is ______.

A Carnot engine has efficiency of 50%. If the temperature of sink is reduced by 40°C, its efficiency increases by 30%. The temperature of the source will be ______.

The efficiency of a Carnot's engine, working between steam point and ice point, will be ______.

Consider two satellites S₁ and S₂ with periods of revolution 1 hr, and 8 hr, respectively revolving around a planet in circular orbits. The ratio of angular velocity of satellite S₁ to the angular velocity of satellite S₂ is ______.