JEE Main 2021 Physics Paper: 27 Aug, Shift 2

An ac circuit has an inductor and a resistor of resistance R in series, such that XL = 3R. Now, a capacitor is added in series such that XC = 2R. The ratio of new power factor with the old power factor of the circuit is $\sqrt{5}:x$. The value of x is ___________.

X different wavelengths may be observed in the spectrum from a hydrogen sample if the atoms are excited to states with principal quantum number n = 6? The value of X is ______________.

Three capacitors C1 = 2$\mu$F, C2 = 6$\mu$F and C3 = 12$\mu$F are connected as shown in figure. Find the ratio of the charges on capacitors C1, C2 and C3 respectively:

The ratio of the equivalent resistance of the network (shown in figure) between the points a and b when switch is open and switch is closed is x: 8. The value of x is ___________.

For full scale deflection of total 50 divisions, 50 mV voltage is required in galvanometer. The resistance of galvanometer if its current sensitivity is 2 div/mA will be:

The Colour coding on a carbon resistor is shown in the given figure. The resistance value of the given resistor is:

A monochromatic neon lamp with wavelength of 670.5 nm illuminates a photo-sensitive material which has a stopping voltage of 0.48 V. What will be the stopping voltage if the source light is changed with another source of wavelength of 474.6 nm?

A constant magnetic field of 1T is applied in the x > 0 region. A metallic circular ring of radius 1m is moving with a constant velocity of 1 m/s along the x-axis. At t = 0s, the centre of O of the ring is at x = $-$1m. What will be the value of the induced emf in the ring at t = 1s? (Assume the velocity of the ring does not change.)

A plane electromagnetic wave with frequency of 30 MHz travels in free space. At particular point in space and time, electric field is 6 V/m. The magnetic field at this point will be x $\times$ 10$-$8 T. The value of x is ___________.

Figure shows a rod AB, which is bent in a 120$^\circ$ circular arc of radius R. A charge ($-$Q) is uniformly distributed over rod AB. What is the electric field $\vec{E}$at the centre of curvature O?

A mass of 50 kg is placed at the centre of a uniform spherical shell of mass 100 kg and radius 50 m. If the gravitational potential at a point, 25 m from the centre is V kg/m. The value of V is:

if the rms speed of oxygen molecules at 0${}^\circ$C is 160 m/s, find the rms speed of hydrogen molecules at 0${}^\circ$C.

The boxes of masses 2 kg and 8 kg are connected by a massless string passing over smooth pulleys. Calculate the time taken by box of mass 8 kg to strike the ground starting from rest. (use g = 10 m/s2)

Wires W1 and W2 are made of same material having the breaking stress of 1.25 $\times$ 109 N/m2. W1 and W2 have cross-sectional area of 8 $\times$ 10−7 m2 and 4 $\times$ 10−7 m2, respectively. Masses of 20 kg and 10 kg hang from them as shown in the figure. The maximum mass that can be placed in the pan without breaking the wires is ____________ kg. (Use g = 10 m/s2)

Water drops are falling from a nozzle of a shower onto the floor, from a height of 9.8 m. The drops fall at a regular interval of time. When the first drop strikes the floor, at that instant, the third drop begins to fall. Locate the position of second drop from the floor when the first drop strikes the floor.

A coaxial cable consists of an inner wire of radius 'a' surrounded by an outer shell of inner and outer radii 'b' and 'c' respectively. The inner wire carries an electric current i0, which is distributed uniformly across cross-sectional area. The outer shell carries an equal current in opposite direction and distributed uniformly. What will be the ratio of the magnetic field at a distance x from the axis when (i) x < a and (ii) a < x < b?

Two simple harmonic motion, are represented by the equations $y_1 = 10\sin\left(3\pi t + \frac{\pi}{3}\right) \quad y_2 = 5(\sin 3\pi t + \sqrt{3}\cos 3\pi t)$ Ratio of amplitude of y1 to y2 = x: 1. The value of x is ______________.

A player kicks a football with an initial speed of 25 ms${}^{-1}$ at an angle of 45$^\circ$ from the ground. What are the maximum height and the time taken by the football to reach at the highest point during motion? (Take g = 10 ms${}^{-2}$)

Curved surfaces of a plano-convex lens of refractive index $\mu$1 and a plano-concave lens of refractive index $\mu$2 have equal radius of curvature as shown in figure. Find the ratio of radius of curvature to the focal length of the combined lenses.

Two discs have moments of inertia I1 and I2 about their respective axes perpendicular to the plane and passing through the centre. They are rotating with angular speeds, $\omega$1 and $\omega$2 respectively and are brought into contact face to face with their axes of rotation coaxial. The loss in kinetic energy of the system in the process is given by:

For a transistor $\alpha$ and $\beta$ are given as $\alpha = \frac{I_C}{I_E}$ and $\beta = \frac{I_C}{I_B}$. Then the correct relation between $\alpha$ and $\beta$ will be:

A zener diode of power rating 2W is to be used as a voltage regulator. If the zener diode has a breakdown of 10 V and it has to regulate voltage fluctuated between 6 V and 14 V, the value of Rs for safe operation should be ___________ $\Omega$.

A heat engine operates between a cold reservoir at temperature T2 = 400 K and a hot reservoir at temperature T1. It takes 300 J of heat from the hot reservoir and delivers 240 J of heat to the cold reservoir in a cycle. The minimum temperature of the hot reservoir has to be ______________ K.

The height of Victoria falls is 63 m. What is the difference in temperature of water at the top and at the bottom of fall?

[Given 1 cal = 4.2 J and specific heat of water = 1 cal g$^{-}$1 $^{\circ}\text{C}^{-}$1]

If force (F), length (L) and time (T) are taken as the fundamental quantities. Then what will be the dimension of density:

Match List - I with List - II.

Choose the most appropriate answer from the options given below:

A tuning fork is vibrating at 250 Hz. The length of the shortest closed organ pipe that will resonate with the tuning fork will be __________ cm. (Take speed of sound in air as 340 ms${}^{-1}$)

The light waves from two coherent sources have same intensity I1 = I2 = I0. In interference pattern the intensity of light at minima is zero. What will be the intensity of light at maxima?